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At least 217 records · Page 12Linked to original sources
PubMed2000

The integration of digital camera derived images with a computer based diabetes register for use in retinal screening.

Exeter district provides a retinal screening service based on a mobile non-mydriatic camera operated by a dedicated retinal screener visiting general practices on a 2-yearly cycle. Digital attachments to eye cameras can now provide a cost effective alternative to the use of film in population based eye screening programmes. Whilst the manufacturers of digital cameras provide a database for the storage of pictures, the images do not as yet interface readily with the rest of the patient's computer held data or allow for a sophisticated grading, reporting and administration system. The system described is a development of the Exeter diabetes register (EXSYST) which can import digitally derived pictures from either Ris-Lite TM and Imagenet TM camera systems or scanned Polaroids Pictures can be reported by the screener, checked by a consultant ophthalmologist via the hospital network, and a report, consisting of colour pictures, map of relevant pathology and referral recommendations produced. This concise report can be hard copied inexpensively on a high resolution ink-jet printer to be returned to the patient's general practitioner. Eye images remain available within the hospital diabetes centre computer network to facilitate shared care. This integrated system would form an ideal platform for the addition of computer based pathology recognition and total paperless transmission when suitable links to GP surgeries become available.

Blindness↗
PubMed1986

A lymphoma plasma membrane-associated protein with ankyrin-like properties.

In this study we have used several complementary techniques to isolate and characterize a 72-kD polypeptide that is tightly associated with a major mouse T-lymphoma membrane glycoprotein, gp 85 (a wheat germ agglutinin-binding protein), in a 16 S complex. These two proteins do not separate in the presence of high salt but can be dissociated by treatment with 2 M urea. Further analysis indicates that the 72-kD protein has ankyrin-like properties based on the following criteria: (a) it cross-reacts with specific antibodies raised against erythrocyte and brain ankyrin; (b) it displays a peptide mapping pattern and a pI (between 6.5 and 6.8) similar to that of the 72-kD proteolytic fragment of erythrocyte ankyrin; (c) it competes with erythrocyte ghost membranes (spectrin-depleted preparations) for spectrin binding; and (d) it binds to purified spectrin and fodrin molecules. Most importantly, in intact lymphoma cells this ankyrin-like protein is localized directly underneath the plasma membrane and is found to be preferentially accumulated beneath receptor cap structures as well as associated with a membrane-cytoskeleton complex preparation. It is proposed that the ankyrin-like 72-kD protein may play an important role in linking certain surface glycoprotein(s) to fodrin which, in turn, binds to actin filaments required for lymphocyte cap formation.

Animals↗
PubMed1991

Human Zn-alpha 2-glycoprotein cDNA cloning and expression analysis in benign and malignant breast tissues.

Two cDNA clones coding for Zn-alpha 2-glycoprotein (Zn-alpha 2-gp) have been isolated from a human breast library and their nucleotide sequences determined. The deduced amino acid sequence contains the coding information for a hydrophobic signal peptide and the 278 residues of the mature protein. Comparison of this sequence with that from the protein purified from plasma reveals four differences: two amino acid changes (Gln-67 and Glu-222) and insertion of two residues (Ile-75 and Phe-76). Northern-blot analysis showed that the Zn-alpha 2-gp gene is expressed in liver and normal breast, but not in placenta, ovary and thyroid. A comparative analysis in mammary tissues from women with different diseases revealed enhanced expression of Zn-alpha 2-gp gene in benign breast lesions and a variable expression level in breast cancers.

Amino Acid Sequence↗
PubMed2000

Identification of a novel hybrid glycophorin gene encoding GP.Hop.

BACKGROUND: The GP.Hop (Mi.IV) phenotype expresses the MNS low-incidence antigens Mur, Hop, TSEN, MINY, and MUT. Because serologically similar MNS phenotypes expressing some or all of these antigens were shown to be carried by hybrid GP(B-A-B) proteins, it was proposed that a similar protein would be found for GP.Hop. The identification of a second GP.Hop propositus (ES) initiated a study to determine the molecular basis of this phenotype. STUDY DESIGN AND METHODS: Serologic tests and immunoblotting analysis with glycophorin-specific antibodies were performed. GYPB, the gene encoding the GPB protein, was cloned and sequenced after reverse transcription PCR amplification of total RNA isolated from ES. GYPB-specific primers encompassing GYPB pseudoexon 3, intron 3, and exon 4 were also used to clone and sequence genomic DNA from ES and MH, the original GP.Hop proband. RESULTS: Serologic and immunochemical data confirmed that ES's RBCs carried antigens associated with the GP.Hop phenotype. Sequencing of ES's cDNA demonstrated the presence of genes predicted to encode s-specific GPB and an S-specific GP(B-A-B) hybrid in which the 3' end of GYPB pseudoexon 3 had been replaced by a short nucleotide sequence from exon 3 of the GPA gene (GYPA). The hybrid nucleotide sequence contained sequence motifs previously shown to be required for the expression of the Mur, Hop, TSEN, MINY, and MUT, which is consistent with their presence as detected serologically. Genomic DNA analysis found that the crossover point in GYPB pseudoexon 3 was identical in ES and MH. CONCLUSIONS: The GP.Hop phenotype is produced by a hybrid GP(B-A-B) protein caused by a DNA insertion of GYPA into GYPB. The composition of the hybrid protein is GPB(1-26)-GPpsiB(27-50)-GPA(51-58)-GPB(S)(59-103).

Amino Acid Sequence↗
PubMed2002

Failure of single-unit neuronal activity to differentiate globus pallidus internus and externus in Parkinson disease.

OBJECT: The authors examine the validity of single-unit neuronal recordings as a method of differentiating the globus pallidus internus (GPi) from the GP externus (GPe) in Parkinson Disease. METHODS: One hundred twenty-eight recordings of apparent single-unit activity used to help guide final electrode placement in eight patients who underwent pallidotomy were analyzed using sophisticated spike sorting methods, and 185 neurons were characterized for mean firing frequency and percent of firing within bursts. In addition, the total spectral power was calculated on the full measured waveform for each of 128 samples without spike sorting. No correlation was identified between these measures of neuronal activity and depth within the GP. CONCLUSIONS: These results call into question the validity of relying on single-unit activity and microelectrode recordings in the operating room to localize lesion or electrode placement within the GPi during stereotactic pallidal surgery.

Action Potentials↗
PubMed1990

Characterization of the human platelet glycoprotein IIIa gene. Comparison with the fibronectin receptor beta-subunit gene.

This study was designed to determine the structure of the gene for glycoprotein (GP) GPIIIa, the beta-subunit of the platelet membrane GPIIb-IIIa complex. The complexity of the gene was determined after Southern analysis of human chromosomal DNA. Overlapping genomic clones were isolated from cosmid and phage lambda libraries that contained the entire coding unit of the human gene for the mature GPIIIa protein. The genomic clones spanned approximately 60 kilobase pairs of human DNA sequence. The exon containing segments of the clones was mapped and the exons, including the exonintron junctions, were sequenced. The GPIIIa protein is divided into 14 exons ranging in size from 87 to 430 nucleotides separated by introns, which were 0.3 to 9 kilobase pairs in size. The 3' exon was larger than 1700 nucleotides and contained the 3'-untranslated region. Several structural domains of the GPIIIa protein were contained within individual exons. These included (i) the transmembrane spanning segment, (ii) the cytoplasmic region containing the potential phosphorylation sites, and (iii) the six domains in the NH2-terminal half of GPIIIa that are highly conserved between two other integrin beta-subunits. In contrast, other domains such as the four cysteine-rich repeats were interrupted by introns. Genomic clones for the beta-subunit of the fibronectin receptor (beta 1) were also isolated, partially mapped, and sequenced. Of the eight splice sites identified in beta 1, six occurred at the same amino acid residue in GPIIIa. These results provide genetic evidence that GPIIIa and beta 1 have a common evolutionary origin within the integrin family.

Amino Acid Sequence↗
PubMed1995

Motor function in a patient with bilateral lesions of the globus pallidus.

This study describes the long-term deficits of a patient who, after a toxic encephalopathy, sustained extensive bilateral damage to both segments of the globus pallidus (GP) and the right substantia nigra (SN). There were no signs of lesions of the pyramidal tracts or of other motor structures. The most obvious deficits were an abnormal gait with an exaggerated knee extension and a tendency to fall slowly, especially when pushed backward. In contrast, Romberg's test on an unstable platform was normal, as were long-latency leg reflexes induced by perturbations. Inadequate anticipatory and compensatory postural responses, in particular across the hip and knee joints, and slow movements seemed responsible for the falls. Muscle tone was normal but reflex studies showed signs of abnormal facilitation and inhibition at various levels of the neuraxis. We conclude that the GP and SN lesions caused defective input to premotor cortical and brain stem target zones. Dysfunctioning of these zones leads to improper control of the descending ventromedial motor system responsible for locomotion, postural control, and reflex status. The deficits in upper extremity motor performance included delayed and slow movements, inaccurate amplitudes of ballistic responses, a lack of predictive control, and deficits in bimanual coordination. Sensory feedback, proprioceptive more than visual, played a powerful compensating role in rapid aiming movements. Regional blood flow (studied using 15(O)2) was reduced in multiple frontal cortical regions, among which are the hand areas of the supplementary and premotor cortex. We hypothesize that this reflected impaired functioning of these areas, caused by defective bilateral output from GP and SN, and resulting in the motor deficits of the arm and hand.

Adult↗
PubMed1985

Movement and non-movement related pallidal unit activity during bar press feeding behavior in the monkey.

Activity was recorded from 358 neurons in the globus pallidus (GP) of monkeys (Macaca fuscata) during an operant feeding task consisting of 3 stages: (1) food or non-food presentation (1st stage); (2) bar pressing (2nd stage); and (3) food acquisition and ingestion (3rd stage). There were two kinds of neurons, one with high and the other with very low (almost silent), spontaneous firing rates. Two hundred and four neurons (57%) responded in one or more of the feeding stages. Of the 21 neurons which responded in the 1st stage, two responded selectively to food presentation, and 19 responded to both food and non-food visual presentation. One hundred and seventy-four neurons (49%) and 107 neurons (30%) responded in the 2nd and 3rd stages, respectively, and 106 (30%) of these were directly related to specific feeding motor acts such as arm extension, flexion, bar pressing, grasping, chewing etc. Both high and low firing neurons responded to motor acts with sharp or gradual onset. More than half of those that responded to arm extension showed laterality (contra or ipsi)- and function (extension or flexion)-dependent responses. The incidence of the motor related neurons was higher in the caudodorsal part of the GP. On the other hand, about one third, especially in the rostroventral part of the GP, showed dissociating responses in that they responded during bar pressing for food or during ingestion in an operant task, but not during bar pressing for non-food or during forcible ingestion. The magnitude of firing changes during arm extension and bar pressing depended on the nature of the food. Moreover, in trials using new food or false (model) food, firing changes during bar press appeared or disappeared within a few trials with no correlation to bar press movement. These data suggest heterogeneous functions within the GP; the caudodorsal part is strictly concerned with motor execution and preparation, while the rostroventral part is not related to motor function directly, but may rather be important in coupling internal, motivational information to the motor system.

Animals↗
PubMed2005

What's in a care pathway? Towards a cultural cartography of the new NHS.

Maps are increasingly understood as socio-cultural and political constructs, rather than mirrors of nature. Drawing on the insights of cultural cartographers, this paper presents a critical analysis of a specific instance of map-making in health policy, namely the growing use of care pathways in care planning and service delivery. Widely regarded to date as devices for ensuring quality of care, equity of treatment, optimal resource allocation and a rational division of labour between healthcare professionals, they have been seen as helpful--and technically neutral--tools for routing patients through the system. By contrast, we argue that the metaphors are misleading: lived experience and its objectification in pathway maps continually re-create one another, as we explore the slippage between map, map-making and mapping. This paper is based on interviews and observations with a variety of healthcare workers in three areas of south eastern England. We trace the development of a series of pathways-in-process, and show how they configure the patient, highlighting some aspects of their experiences, whilst silencing others. We also analyse the role of pathways in the carving up and surveillance of space round the emergence of the 'hybrid professional', particularly new practitioners such as GP specialists, specialist nurses, extended scope therapists and others. In considering the wider implications of care pathways as part of the contemporary discourse on policy, the paper critiques the rationalist, and sometimes evangelical assumptions underpinning their current popularity. In particular, we suggest that a critical and processual understanding of pathways might contribute to a more informed appreciation of their potential (and their limitations) as mechanisms for healthcare policy implementation.

Critical Pathways↗
PubMed2006

Dopamine (D2/3) receptor agonist positron emission tomography radiotracer [11C]-(+)-PHNO is a D3 receptor preferring agonist in vivo.

[11C]PHNO is a recently introduced agonist to image DA D2-like receptors with Positron Emission Tomography (PET). In cats and humans, [11C]PHNO revealed an atypical distribution compared to radiolabeled D2-like antagonists (such as [11C]raclopride) or other D2-like agonists (such as [11C]NPA), as it displayed unusual high binding in the globus pallidus (GP). The goal of this study was to assess the pharmacological nature of the binding of [11C]PHNO in the GP in nonhuman primates. As previously reported in humans, [11C]PHNO equilibrium specific to nonspecific equilibrium partition coefficients (V3'') in baboons was much higher in GP (3.88 +/- 1.15) than in the dorsal striatum (DST, 2.07 +/- 0.43), whereas the reverse was true for [11C]raclopride (1.48 +/- 0.41 in GP, 2.56 +/- 0.91 in DST) and [11C]NPA (0.87 +/- 0.19 in GP, 1.02 +/- 0.13 in DST). Administration of unlabeled raclopride resulted in similar reductions of [11C] PHNO V3'' and [11C]raclopride V3'' in both the GP and the DST. This observation demonstrated that the [11C]PHNO binding in the GP was specific to D2-like receptors. To evaluate the respective contribution of D3 and D2 receptors to the binding potential (BP) of [11C]PHNO and [11C]raclopride, experiments were carried out with the selective D3 partial agonist 1-(4(2-Napthoylamino)butyl)-4-(2-methoxyphenyl)-1A-piperazine HCL (BP897). BP897 reduced [11C]raclopride V3'' by 29% +/- 9%, 19% +/- 8%, and 10% +/- 7% in GP, VST, and DST, respectively, a result consistent with expectation from postmortem studies (D3/D2 ratio in GP > VST > DST). BP897 reduced [11C]PHNO V3'' by 57% +/- 11%, 30% +/- 11%, and 13% +/- 8% in GP, VST, and DST, respectively, indicating that the D3 receptor contribution to [11C]PHNO signal is higher than that of [11C]raclopride. From these experiments we conclude that [11C]PHNO is a D3 preferring agonist, and that this property explains the high GP signal not observed with [11C]raclopride or [11C]NPA. This property might contribute to its higher vulnerability to endogenous DA compared to [11C]raclopride and [11C]NPA.

Animals↗
PubMed1997

Use of domain-deletion mutants to locate Lutheran blood group antigens to each of the five immunoglobulin superfamily domains of the Lutheran glycoprotein: elucidation of the molecular basis of the Lu(a)/Lu(b) and the Au(a)/Au(b) polymorphisms.

Lutheran glycoprotein (Lu gp) has five predicted immunoglobulin superfamily (IgSF) domains. K562 cells were transfected with Lu cDNA and tested by flow cytometry with monoclonal antibodies and Lu blood group antisera. The results confirmed the identity of Lu cDNA. Deletion mutants lacking the regions encoding one or more IgSF domains were made by inverse polymerase chain reaction (PCR), expressed in K562 cells, and tested with the same antibodies. The Lu(b) and Lu5 antigens and the epitope recognized by monoclonal antibody BRIC 224 were mapped to the first, N-terminal, IgSF domain. Lu4 and Lu8 were mapped to domain 2; Lu20 to domain 3; Lu7 and BRIC 221 epitope to domain 4, and Lu13 and Au(b) to domain 5. The organization of the LU gene was determined. The region encoding the open reading frame is arranged in 15 exons extending over approximately 11 kb on chromosome 19q13.2. The Lu(a)/Lu(b) and Au(a)/Au(b) blood group polymorphisms were studied using genomic DNA from typed blood donors. The Lu(a) mutation is a base change in exon 3 (G252 to A) encoding an Arg77 (Lu(b)) to His (Lu(a)) change on the CFG face of domain 1. The Au(a)/Au(b) polymorphism is an A1637 to G substitution in exon 12 encoding a Thr539 (Au(a)) to Ala (Au(b)) change on the G strand of domain 5.

Cell Line↗
PubMed2006

The Barents project in psychiatry: a systematic comparative mental health services study between Northern Norway and Archangelsk County.

BACKGROUND: There is virtually no readily accessible systematically recorded evidence on how the organization of mental health services in Europe's largest country, Russia, may differ from other national systems. This study systematically compares the mental health services in Archangelsk County and Northern Norway using instruments developed for trans-cultural use. METHODS: The European Service Mapping Schedule (ESMS) and The International Classification of Mental Health Care (ICMHC) were used to describe: (i) resources, organisation and utilisation of the services; (ii) their decentralisation and differentiation; (iii) some interventions delivered by the mental health service units (n = 132) in both regions. RESULTS: The Norwegian services are more decentralised and differentiated, while the Russian services are largely hospital-based. The GPs are of considerable importance to the Norwegian services, functioning as gatekeepers-both centrally and peripherally. In contrast, the GP model is still poorly established in Archangelsk County. There are more units for long term stay in the Russian services than in Norway. General health care and taking over daily living activities are more organised in Archangelsk County, while psychopharmacological treatment and psychosocial interventions are more developed in Norway. CONCLUSION: The study has revealed several differences in resources, organisation and utilisation of the mental health services between the two compared areas. The very large variations indicate that underlying local patterns of service delivering must be further investigated and taken into account in the planning of the services development.

Catchment Area, Health↗
PubMed2005

Modulation of the interleukin-6 receptor subunit glycoprotein 130 complex and its signaling by LMO4 interaction.

The interleukin (IL)-6-type cytokines play major roles in a variety of biological processes by signaling through a common receptor subunit, glycoprotein (gp) 130. We performed yeast two-hybrid screening to identify new binding partners of the activated gp130 and the associated Janus kinases. LMO4, a LIM domain-containing protein that belongs to a family of oncogenes, was identified in this assay. Further studies show that LMO4 associates with gp130 and Janus kinase1 in several mammalian cell types. It also interacts with protein-tyrosine phosphatase 2 (SHP2) and suppressor of cytokine signaling 3 (SOCS3). The binding domains involved in these interactions were mapped, and the interactions were shown to be in a direct manner by in vitro binding assays. It is likely that LMO4 exists in the gp130 complex. The cellular localization of LMO4 was detected primarily in the nucleus with a substantial amount also detected in the cytoplasm in several cell types. The effect of LMO4 in IL-6 signaling was subsequently examined. Overexpression of LMO4 enhanced the transcriptional activity and target gene expression of Stat 3 (signal transducers and activators of transcription 3). Consistent with this, silencing LMO4 expression in stable cell lines expressing the small interfering RNA of LMO4 decreased Stat3 activity. Furthermore, the half-life of gp130 was shortened, and the production of acute phase proteins induced by IL-6 was reduced. Together, our data reveal a positive regulatory role of LMO4 in IL-6 signaling, possibly by acting as a scaffold for stabilization of the gp130 complex. These studies may open up a link between the oncogenic effect of LMO proteins and their regulatory role in cytokine signaling in general.

Adaptor Proteins, Signal Transducing↗
PubMedDate not supplied

Comparison between the three porcine RN genotypes for growth, carcass composition and meat quality traits.

A three-step experimental design has been carried out to add evidence about the existence of the RN gene, with two segregating alleles RN- and rn+, having major effects on meat quality in pigs, to estimate its effects on production traits and to map the RN locus. In the present article, the experimental population and sampling procedures are described and discussed, and effects of the three RN genotypes on growth and carcass traits are presented. The RN genotype had no major effect on growth performance and killing out percentage. Variables pertaining to carcass tissue composition showed that the RN- allele is associated with leaner carcasses (about 1 s.d. effect without dominance for back fat thickness, 0.5 s.d. effect with dominance for weights of joints). Muscle glycolytic potential (GP) was considerably higher in RN- carriers, with a maximum of a 6.85 s.d. effect for the live longissimus muscle GP. Physico-chemical characteristics of meat were also influenced by the RN genotype in a dominant way, ultimate pH differing by about 2 s.d. between homozygous genotypes and meat colour by about 1 s.d. Technological quality was also affected, with a 1 s.d. decrease in technological yield for RN- carriers. The RN genotype had a more limited effect on eating quality. On the whole, the identity between the acid meat condition and the RN- allele effect is clearly demonstrated (higher muscle GP, lower ultimate pH, paler meat and lower protein content), and the unfavourable relationship between GP and carcass lean to fat ratio is confirmed.

Journal Article↗
PubMed2001

Alterations in cortical and basal ganglia levels of opioid receptor binding in a rat model of l-DOPA-induced dyskinesia.

Opioid receptor-binding autoradiography was used as a way to map sites of altered opioid transmission in a rat model of l-DOPA-induced dyskinesia. Rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathways sustained a 3-week treatment with l-DOPA (6 mg/kg/day, combined with 12 mg/kg/day benserazide), causing about half of them to develop dyskinetic-like movements on the side of the body contralateral to the lesion. Autoradiographic analysis of mu-, delta-, and kappa-opioid binding sites was carried out in the caudate-putamen (CPu), the globus pallidus (GP), the substantia nigra (SN), the primary motor area, and the premotor-cingulate cortex. The dopamine-denervating lesion alone caused an ipsilateral reduction in opioid radioligand binding in the CPu, GP, and SN, but not in the cerebral cortex. Chronic l-DOPA treatment affected opioid receptor binding in both the basal ganglia and the cerebral cortex, producing changes that were both structure- and receptor-type specific, and closely related to the motor response elicited by the treatment. In the basal ganglia, the most clear-cut differences between dyskinetic and nondyskinetic rats pertained to kappa opioid sites. On the lesioned side, both striatal and nigral levels of kappa binding densities were significantly lower in the dyskinetic group, showing a negative correlation with the rats' dyskinesia scores on one hand and with the striatal expression of opioid precursor mRNAs on the other hand. In the cerebral cortex, levels of mu and delta binding site densities were bilaterally elevated in the dyskinetic group, whereas kappa radioligand binding was specifically increased in the nondyskinetic cases and showed a negative correlation with the rats' dyskinesia scores. These data demonstrate that bilateral changes in cortical opioid transmission are closely associated with l-DOPA-induced dyskinesia in the rat. Moreover, the fact that dyskinetic and nondyskinetic animals often show opposite changes in opioid radioligand binding suggests that the motor response to l-DOPA is determined, at least in part, by compensatory adjustments of brain opioid receptors.

Animals↗
PubMed1991

The gene encoding rat liver glycogen phosphorylase contains multiple polyadenylation signal sequences.

RNA blot analysis of rat liver and adipose tissues detected two glycogen phosphorylase (GP)-encoding transcripts. The polymerase chain reaction was used to characterize the 3'-noncoding region of the gene (L-GP) encoding liver-GP (L-GP) from the lean Zucker rat (Fa/Fa). Three distinct classes of colinear cDNA clones were identified by nucleotide (nt) sequence analysis, demonstrating that the L-GP gene contains at least three functional polyadenylation sites. The predominant L-GP transcript was generated by polyadenylation 130 nt 3' from the end of the coding region. A previously uncharacterized L-GP transcript is generated by polyadenylation at 346 nt 3' of the first polyadenylation site. Polyadenylation site selection does not appear to be regulated in a tissue-specific fashion. The relative steady-state L-GP mRNA levels in the different types of adipose tissues were comparable to, or exceeded transcript levels in liver.

Adipose Tissue↗
PubMed1993

Expression and characterization of functionally active fragments of the platelet glycoprotein (GP) Ib-IX complex in mammalian cells. Incorporation of GP Ib alpha into the cell surface membrane.

The platelet glycoprotein Ib-IX complex (GP Ib-IX) is essential for the initial attachment of platelets to the wall of damaged arteries. In this study, an N-terminal fragment of human GP Ib alpha (residues 1-318), containing the ligand binding sites for von Willebrand factor (vWF) and thrombin, as well as the entire human GP Ib alpha were expressed in Chinese hamster ovary cells. The transfected cells secreted a 48- and a 110-kDa protein, respectively, into the supernatant. Both recombinant proteins were purified by immunoaffinity chromatography. The purified proteins bound soluble vWF in the presence of botrocetin as demonstrated in solid-phase binding assays. The dissociation constant (Kd) for 125I-vWF binding to the recombinant 110-kDa protein was 1.2 +/- 0.2 nM as compared with 1.0 +/- 0.3 nM for vWF binding to purified platelet GP Ib-IX. Both recombinant proteins were also retained on thrombin-Sepharose 4B. The 48-kDa protein contained two N-linked oligosaccharide chains. A 125-kDa protein was identified in the lysate of cells transfected with the coding sequence for the entire GP Ib alpha. Trypsin treatment of this protein generated a 110-kDa fragment, whereas the secreted 110-kDa protein remained unchanged. Post-translational removal of the C-terminal transmembrane domain of recombinant GP Ib alpha might have facilitated the secretion of the soluble glycocalicin-like 110-kDa fragment. In addition, flow cytometry and immunofluorescence microscopy demonstrated that the expression of GP Ib alpha alone is sufficient for its incorporation into the cell surface membrane. These data indicate that two soluble fragments of human GP Ib alpha with binding activity for vWF and thrombin can be expressed in mammalian cells and that the incorporation of GP Ib alpha into the surface membrane does not depend on co-expression with GP Ib beta and/or GP IX.

Animals↗
PubMed2005

Comprehensive analysis of ebola virus GP1 in viral entry.

Ebola virus infection is initiated by interactions between the viral glycoprotein GP1 and its cognate receptor(s), but little is known about the structure and function of GP1 in viral entry, partly due to the concern about safety when working with the live Ebola virus and the difficulty of manipulating the RNA genome of Ebola virus. In this study, we have used a human immunodeficiency virus-based pseudotyped virus as a surrogate system to dissect the role of Ebola virus GP1 in viral entry. Analysis of more than 100 deletion and amino acid substitution mutants of GP1 with respect to protein expression, processing, viral incorporation, and viral entry has allowed us to map the region of GP1 responsible for viral entry to the N-terminal 150 residues. Furthermore, six amino acids in this region have been identified as critical residues for early events in Ebola virus entry, and among these, three are clustered and are implicated as part of a potential receptor-binding pocket. In addition, substitutions of some 30 residues in GP1 are shown to adversely affect GP1 expression, processing, and viral incorporation, suggesting that these residues are involved in the proper folding and/or overall conformation of GP. Sequence comparison of the GP1 proteins suggests that the majority of the critical residues for GP folding and viral entry identified in Ebola virus GP1 are conserved in Marburg virus. These results provide information for elucidating the structural and functional roles of the filoviral glycoproteins and for developing potential therapeutics to block viral entry.

Amino Acid Sequence↗