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At least 199 records · Page 11Linked to original sources

On crossed apraxia. Description of a right-handed apraxic patient with right supplementary motor area damage.

GP, a right-handed woman, without evidence of familial left-handedness, showed clearcut bilateral ideo-motor apraxia and oro-facial apraxia after a vascular lesion of the right hemisphere, encroaching upon the fronto-mesial region. She scored normally in most other cognitive tests, including language, but showed signs of callosal disconnection, left anarchic hand and mild unilateral spatial neglect. This cognitive profile points to the possibility of praxis being localized to the right hemisphere in this right-handed patient. We argue in favour of individual variability of praxis dominance, and maintain that this dominance might be completely right-sided in some subjects. Moreover the anatomical locus of GP's lesion points to the possible role that the frontal lobes (and more specifically the Supplementary Motor Area) play in the genesis of apraxia.

Agnosia↗

Basal ganglia involvement in memory-guided movement sequencing.

The basal ganglia (BG) are thought to play a critical role in motor planning and movement sequencing. While electrophysiological and imaging studies have shown that the dorso-lateral prefrontal cortex (DLPFC) is involved in working memory (WM), the involvement of the BG in this process is not well understood. We used a motor sequencing task to investigate the differential role of BG nuclei in memory-guided movement. Significant activation was observed in the DLPFC and posterior putamen and globus pallidus (GP), with a trend in the caudate and no differences in the anterior putamen. We then investigated the effect of BG outflow on thalamic activation using functional connectivity analysis. Activation in the posterior putamen + GP was found to be correlated with thalamic activation only in the hemisphere contralateral to movement. These results provide the first fMRI evidence that the BG may modulate activity in the thalamus during working memory-guided movement sequencing. Our findings suggest that the BG activation may reflect increased motor sequencing demands during the memory-guided movement condition and, specifically, that the posterior putamen and GP may play a role in maintenance of representations in WM in a manner that contributes to planning and temporal organization of motor sequencing.

Adult↗

The critical interaction of glycoprotein (GP) IBbeta with GPIX-a genetic cause of Bernard-Soulier syndrome.

Bernard-Soulier syndrome is an uncommon bleeding disorder caused by a quantitative or qualitative defect in the platelet glycoprotein (GP)Ib/IX complex. The complex is composed of four subunits, GPIbalpha, GPIbbeta, GPIX, and GPV. Here we describe the molecular basis of a novel Bernard-Soulier syndrome variant in a patient in whom GPIbalpha and GPIX were undetectable on the platelet surface. DNA sequence analysis showed normal sequence for GPIbalpha, GPIX, and GPV. The GPIbbeta gene has been mapped to the 22q11.2 region of chromosome 22 which was deleted from one chromosome of this patient. There was a single nucleotide deletion within the codon for Ala 80 in GPIbbeta within the other allele. This mutation causes a translational frame shift that encodes for 86 altered amino acids and predicts a premature stop 15 amino acids short of the length of the wild-type protein. Transient coexpression of the mutant GPIbbeta in 293T cells with wild-type GPIbalpha and GPIX resulted in the surface expression of GPIbalpha, but the absence of GPIX. Moreover, when a plasmid encoding the wild-type GPIbbeta was transiently transfected into Chinese hamster ovary cells stably expressing GPalpha, which retain the capacity to reexpress GPIX, there was a significant increase in the surface expression of GPIX. In contrast, when the mutant GPIbbeta was transiently transfected into these cells, GPIX was not reexpressed on the plasma surface. Thus, a deletion of one copy of GPIbbeta and a single nucleotide deletion in the codon for Ala 80 within the remaining GPIbbeta allele causes the Bernard-Soulier phenotype through an interaction of GPIbbeta with GPIX resulting in the absence of GPIbalpha on the plasma membrane. The interaction of GPIbbeta with GPIX is essential for the functional expression of GPIbalpha.

Adolescent↗

Human platelet glycoproteins V and IX: mapping of two leucine-rich glycoprotein genes to chromosome 3 and analysis of structures.

Human platelet glycoproteins Ib alpha, Ib beta, V, and IX comprise an interrelated set of molecules (the Ib-V-IX system) that together form a surface adhesion receptor for the ligand, von Willebrand factor. To complete the primary structural characterization of the genes involved in this system, we have analyzed cosmid clones for both the glycoprotein V and IX genes and used these clones to localize the two genes by fluorescence in situ hybridization. Both genes were found on the long arm of chromosome 3, but at distinct sites, the GPV gene on 3 band q29 and the GP IX gene on 3 band q21. The transcriptional start site of the GPV gene was defined by "anchored" PCR and primer extension. The GPV gene contains two exons, the first consisting of approximately 37 bases and the second of approximately 3500 bases, interrupted by a single 958 base intron. The GPV transcript has multiple start sites spread over a twenty base region. The 5' flanking region of the GPV gene has a series of potential consensus regulatory elements including GATA, ets, and Sp-1 sites, similar to those found in other described megakaryocyte/platelet genes, including those of the Ib-V-IX system. In assessing the four Ib-V-IX genes as a group, all four have a simple, "intron-depleted" structure with the entire open reading frame of the mature polypeptide located within a single exon.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

Different oligosaccharide processing of the membrane-integrated and the secretory form of gp 80 in rat liver.

Rat liver synthesizes a glycoprotein with Mr of 80.000 (gp 80) which is partly inserted into the plasma membrane and partly secreted into the serum. The membrane-integrated and the secretory form of this glycoprotein have an identical peptide pattern, but different N-linked glycans. Whereas gp 80 from the serum is glycosylated with complex-type oligosaccharides, gp 80 from the plasma membrane has high mannose glycans. Phase separation with Triton X-114 showed that membrane-integrated gp 80 contains hydrophobic portions, whereas secretory gp 80 has hydrophilic properties. Intracellular transport and oligosaccharide processing of gp 80 were studied in vivo in the endoplasmic reticulum, the Golgi apparatus and plasma membranes of rat liver and in serum using pulse-chase labeling with L-[35S]methionine and immunoprecipitation. Peak labeling of gp 80 was reached in the endoplasmic reticulum 10 min after the pulse, in the Golgi apparatus 20 min later, and in the plasma membrane after 2 h; in the serum the specific radioactivity was steadily increasing during the experiment. Gp 80 of the endoplasmic reticulum was completely sensitive to endo-beta-N-glucosaminidase H (endo H), but simultaneously occurred in the Golgi apparatus in an endo H-sensitive and endo H-resistant form. The endo H-sensitive form was transported to the plasma membrane, the endo H-resistant species secreted into the serum. Conversion from the endo H-sensitive to the endo H-resistant form was completed within 10 min after transfer of gp 80 to the Golgi apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

In vitro transcription and translation of genomic RNA from a porcine group C rotavirus.

Eleven segments of ssRNA were synthesized from dsRNAs of a porcine group (Gp) C rotavirus (Cowden strain) using an in vitro transcription system. In vitro translation of unfractionated ssRNAs revealed at least nine viral proteins, ranging from 22 kDa to 93 kDa. The 37 kDa and 25 kDa proteins were glycosylated as demonstrated by the endoglycosidase H assay. In vitro translated products analyzed by SDS-polyacrylamide gel electrophoresis and partial protease peptide mapping were comparable to those synthesized in vivo (MA 104 cells).

Animals↗

Effect of a P-glycoprotein inhibitor, Cyclosporin A, on the disposition in rodent brain and blood of the 5-HT1A receptor radioligand, [11C](R)-(-)-RWAY.

Limited brain uptake of radioligands with otherwise optimal properties for imaging brain receptors can be improved by blocking the effect of P-glycoprotein (P-gp), an efflux pump at the blood-brain barrier. Using small animal positron emission tomography (PET), we investigated how P-gp and its blockade with Cyclosporin A (CsA) affect rodent brain uptake of [(11)C](R)-(-)-RWAY, a radioligand for brain 5-HT(1A) receptors. Brain uptake of radioactivity was compared in control and CsA-treated rats as well as P-gp knockout and wild type mice. Parent radioligand and radiometabolite in plasma and brain samples were determined at 30 min after injection of radioligand. PET binding potential (BP) was calculated with a reference tissue model. P-gp knockout mice had 2.5- and 2.8-fold greater brain uptake of [(11)C](R)-(-)-RWAY than wild type ones, measured by in vivo PET and ex vivo tissue sampling, respectively. Similarly, CsA increased rat brain uptake 4.9- and 5.3-fold, in vivo and ex vivo. In addition, CsA increased the plasma free fraction of [(11)C](R)-(-)-RWAY in rats by 2.7-fold. Although CsA increased brain uptake in wild type mice by 2.5-fold, it had no effect on plasma free fraction in knockout animals. Three radiometabolites of [(11)C](R)-(-)-RWAY were uniformly distributed in rat brain, suggesting they were inactive. CsA treatment increased brain uptake of [(11)C](R)-(-)-RWAY and only one of its radiometabolites. Regional rat brain BP increased 27-70% in the CsA-treated rats and the P-gp knockout mice. [(11)C](R)-(-)-RWAY is a P-gp substrate in rat and mouse. The effects of CsA in rats are mediated by both P-gp blockade and displacement of the radiotracer from plasma proteins. Studies with wild type and knockout mice showed that CsA affected only P-gp in this species.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Cloning and nucleotide sequence of a human Zn-alpha 2-glycoprotein cDNA and chromosomal assignment of its gene.

A cDNA clone of Zn-alpha 2-glycoprotein (Zn alpha 2gp) was isolated from a human prostate library. The amino acid sequence of prostate Zn alpha 2gp deduced from the nucleotide sequence was identical to the one previously reported on the Zn alpha 2gp protein purified from human blood plasma, except at three positions: the 65th and 222nd amino acid residues were Gln (----Glu) and Glu (----Gln), and there was a two amino acid insertion (Ile-Phe) between the 75th (Glu) and 76th (Met) amino acids. Southern blot analysis of human genomic DNA, however, suggested a single gene encoding Zn alpha 2gp. Using a panel of rodent-human somatic cell hybrids, the Zn alpha 2 gp gene was assigned to human chromosome 7.

Amino Acid Sequence↗

Defining localities for health planning: a GIS approach.

The National Health Service in Britain is undergoing far-reaching changes. While District and Regional Health Authorities are currently merging, professionals agree that primary health care is most efficiently managed at the local level. This paper uses geographical information systems (GIS) capabilities to identify a nested hierarchy of localities for the management of primary health care in West Sussex, England. GIS coverages were developed which contained key criteria for defining local areas, including nodes or focal points of service provision, edges which act as physical or psychological barriers to movement, districts such as official administrative areas and interaction criteria such as journey to work, school and family doctor (GP) surgeries. Central to the derivation of the localities was a large matrix of patient to GP flows based on postcoded data. Once managed, these data revealed clear geographical patterns of patient to GP allegiance. A large-scale field survey obtained supporting information on the perception of areas from local residents.

Catchment Area, Health↗

The alpha 1-adrenergic photoaffinity probe [125I]arylazidoprazosin binds to a specific peptide of P-glycoprotein in multidrug-resistant cells.

Much evidence suggests that P-glycoprotein (P-gp) confers multidrug-resistance (MDR) in tumor cells by energy-dependent efflux of hydrophobic cytotoxic agents. In this study, we have used the alpha 1-adrenergic photoaffinity probe, [125I]arylazidoprazosin ([125I]AAP), and identified P-gp as a specific acceptor for prazosin. Drugs to which MDR cells are resistant, including vincristine, vinblastine, doxorubicin, actinomycin D and colchicine as well as agents reversing MDR, including verapamil, nicardipine, prenylamine, diltiazem, trifluoperazine, dibucaine, reserpine, monensin, and progesterone, differentially reduced [125I]AAP photolabeling of P-gp. We also analyzed the influence of alpha 2-adrenergic drugs and dopaminergic drugs on [125I]AAP photolabeling of P-gp. Limited proteolysis of [125I]AAP photolabeled P-gp with Staphylococcus aureus V8 protease revealed that prazosin binds to a single 8 kDa fragment of P-gp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Structure of the cell-puncturing device of bacteriophage T4.

Bacteriophage T4 has a very efficient mechanism for infecting cells. The key component of this process is the baseplate, located at the end of the phage tail, which regulates the interaction of the tail fibres and the DNA ejection machine. A complex of gene product (gp) 5 (63K) and gp27 (44K), the central part of the baseplate, is required to penetrate the outer cell membrane of Escherichia coli and to disrupt the intermembrane peptidoglycan layer, promoting subsequent entry of phage DNA into the host. We present here a crystal structure of the (gp5-gp27)3 321K complex, determined to 2.9 A resolution and fitted into a cryo-electron microscopy map at 17 A resolution of the baseplate-tail tube assembly. The carboxy-terminal domain of gp5 is a triple-stranded beta-helix that forms an equilateral triangular prism, which acts as a membrane-puncturing needle. The middle lysozyme domain of gp5, situated on the periphery of the prism, serves to digest the peptidoglycan layer. The amino-terminal, antiparallel beta-barrel domain of gp5 is inserted into a cylinder formed by three gp27 monomers, which may serve as a channel for DNA ejection.

Amino Acid Sequence↗

Lymphocytic choriomeningitis virus. III. Structural proteins of the virion.

Analysis of radioactively labelled and highly purified infectious lymphocytic choriomeningitis (LCM) virus by polyacrylamide gel electrophoresis (PAGE) revealed 12 components which, according to their apparent molecular weight and glycosylation status, were designated as p19, p25, p26, gp35, p38, gp44, gp60, p63, p77, gp85, gp130, and p200. As shown by immunoprecipitation, they all bound to rabbit anti-LCM virus antibodies. Three proteins, namely gp35 (= 'GP-2'), gp44 (= 'GP-1') and p63 (= 'NP'), had previously been described by others as major constituents of the virion. Our results confirm this and suggest that gp60, p77, gp85, and p200 are further distinct structural proteins. In contrast, p25 and p38 appear to be cleavage or degradation products of p63; p19 and p26 seem to belong to gp60, which could be the monomeric form of a dimer, gp130. Peptide mapping by limited proteolysis revealed considerable overlapping of amino acid sequences among the major glycoproteins with one peptide being common to all. From the results of PAGE performed after external labelling of intact virions, we conclude that gp44, gp60, and gp85 (but not gp35) form the surface of the virus envelope. Analytical isoelectric focusing under non-reducing conditions has shown that the major glycoproteins appeared to consist of several components with different isoelectric points.

Electrophoresis, Polyacrylamide Gel↗

P-glycoprotein genes in the winter flounder, Pleuronectes americanus: isolation of two types of genomic clones carrying 3' terminal exons.

In mammals, P-glycoprotein (P-gp) is encoded by two or more highly conserved genes that differ in their abilities to transport drugs. One isoform class (class I) is consistently associated with the multidrug resistance phenotype, while the other (class III) is not. This study was designed to enumerate the P-gp genes in fish and determine how they are related to the two functional classes already defined in mammals. Southern blot analysis using a conserved single exon from the 3' terminal region of hamster P-gp cDNA (pEX1-172) as a probe indicated that there were two P-gp genes in right-eye flounders. Subsequently, two sets of clones were isolated from a winter flounder genomic library that correspond to the 3' ends of the two flounder P-gp genes. Sequence analysis was done on two key areas: the 3' ATP binding site and the 3' terminal exon, both of which were found to be homologous with their mammalian counterparts. Despite high levels of sequence identity in the predicted coding regions of the gene fragments it has not been possible to use these sequences to relate the homologs to particular mammalian classes of P-gp genes, perhaps because of gene conversion between mammalian P-gp genes. These cloned sequences are the first set of P-gp genes reported in lower vertebrates and will be useful for delineating the expression of P-gp genes in fish and understanding the role of P-gp in fish physiology.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Extracellular signal-regulated kinase (ERK) activation is required for GP Ibalpha-dependent endothelial cell migration.

The GP Ib complex can participate in endothelial cell (EC) migration on von Willebrand factor (vWF) or the mixed matrix of vWF and type I collagen (vWF/collagen). In this study, viper venom proteins alboaggregin (albo) A or B blocked GP Ibalpha, and echistatin inhibited alphavbeta3 binding. Albo A, B and echistatin inhibited EC migration on vWF and vWF/collagen. Albo B or the anti-GP Ibalpha monoclonal antibody (mAb) 1b1 did not affect the migration of smooth muscle cells or fibroblasts, which lack GP Ib. EC also migrate on albo A- or albo B-coated dishes. PD98059, which blocks ERK activation, abolished EC migration on vWF, vWF/collagen, collagen or albo B. Soluble albo A or 1b1 dramatically inhibited ERK activation during EC migration on vWF or albo B. Echistatin inhibited ERK activation on vWF and vitronectin (VN), but not albo B. Thus, in addition to alphavbeta3, EC GP Ibalpha initiates ERK activation, and regulates ERK-induced EC migration on vWF.

Antibodies, Monoclonal↗

The role of free radicals and antioxidative enzymes in erythrocytes and liver cells in the course of Plasmodium berghei and Plasmodium vinckei infection of mice.

Blood schisontocidal test of D0 + D3 type revealed different characteristics of the Plasmodium berghei and Plasmodium vinckei infection. Both types of the rodent plasmodia kill the untreated mice. Chloroquine treatment alone does not prevent the death of the P. berghei infected animals and they died at a low level of parasitaemia. The animals cured with chloroquine plus MAP survive. The infection with P. vinckei produces a high level of parasitaemia and the chloroquine treatment alone prevents the death of mice. The difference in the pathogenic characteristics between P. berghei and P. vinckei is manifested in the results measuring the kinetics of the activity of antioxidative enzymes in the red blood and liver cells of the infected mice: lipid peroxidation (LPO), superoxide dismutases (SOD), glutathione peroxidase (GP), catalase (CAT) and reduced glutathione (GSH). The rapid increase of the LPO in the RBC in particular in the P. vinckei infected animals indicates the prevailing role of the membrane detoxification process. A continuous increase in the activity of enzymes of cytoplasmic origin, e.g. SOD and GP was also observed. A powerful increase in GSH distinguishes the erythrocytes of P. vinckei infected animals. Similar but not identical data characterize the enzyme activities of the liver cells of the plasmodia infected animals.

Animals↗

An abundantly secreted glycoprotein from Drosophila melanogaster is related to mammalian secretory proteins produced in rheumatoid tissues and by activated macrophages.

An abundantly secreted 47-kDa glycoprotein, DS47, was purified from Drosophila melanogaster (Dm) Schneider line-2 cells, a line exhibiting macrophage-like properties. DS47 is also secreted from several Dm cell lines resembling S2 but not from lines that are morphologically distinct. A cDNA cline was isolated from an S2 cell cDNA library using oligodeoxyribonucleotide probes based on the DS47 amino acid (aa) sequence and found to encode a novel secretory glycoprotein of 452 aa. Analysis of DS47 protein production and mRNA expression during fly development indicates that both are present throughout the entire Dm life cycle, suggesting that DS47 may be important at all developmental stages. In larvae, the DS47 message is made in the fat body and by hemocytes, and secreted into the hemolymph. DS47 is related to a human cartilage glycoprotein, HC gp-39, that is secreted from cell types associated with the arthritic joint, such as synovial cells and activated macrophages. Interestingly, the HC gp-39 message is most readily detected in the human liver, an organ that is somewhat analogous to the Dm fat body. DS47 also shares homology to a mouse secretory glycoprotein, YM-1, identified in activated macrophages. These homologies extend to the chitinase gene family and include a conserved cysteine aa motif, as well as two blocks of aa within the enzymatic active site, although neither DS-47 nor HC gp-39 exhibit chitinase activity. Potential functions of this conserved protein family are discussed.

Adipokines↗

Effects of the globus pallidus lesion on the induction of c-Fos by dopaminergic drugs in the striatum possibly via pallidostriatal feedback loops.

c-Fos is one of the transcription factors contributing to the regulation of the downstream gene expression. Administration of dopamine D1 receptor agonist or D2 receptor antagonist have been known to induce c-Fos expressions in striatal projection neurons. We examined the effects of unilateral ablation of the globus pallidus (GP) on apomorphine- or haloperidol-induced expression of c-Fos in the striatum. Haloperidol induced a high level of c-Fos expression in the striatal neurons, predominantly those in the dorsal part, and the unilateral GP lesion caused by ibotenic acid increased the number of neurons exhibiting haloperidol-induced c-Fos expression in the striatum on the side with the GP lesion by about 2- or 3-fold. On the other hand, the unilateral GP lesion had no significant effect on the apomorphine-induced c-Fos expression in the striatal neurons. The present study provides evidence indicating that the activity of GP neurons may have an inhibitory influence on the induction of the immediate early genes by haloperidol in the striatal neurons, suggesting a function of the pallido-striatal feedback loops which have been identified anatomically.

Animals↗

Neurophysiological processes in the striopallidum in shaping of avoidance reactions.

Analysis of evoked potentials (EP) (which are criteria of the brain structures' involved in integration processes) dynamics served as a basis to investigate participation of the caudate nucleus (Cd), the globus pallidum (GP) and the thalamus ventrolateral nucleus (VL) in two types of the adaptive behavior securing: defensive avoidance reaction and perception learning. The results prove the notion that neurophysiological processes change in brain structures by adaptive reactions forming in dogs (Adrianov, 1980; Popova, 1980). Goal-directed motor component presence in the adaptive behavior was revealed as the determining factor of the Cd, GP and VL involvement in the system's processes. It was found that the dynamics of the Cd, GP and VL involvement in defensive habit central organization are determined both by motor response forming and signal and reinforcing stimuli functional significance change: the Cd, GP and VL functioning "regime" dependence on relationship were shown between these external elements of the adaptive behavior system. The Cd is involved in the central integration by two variants: the first one is formed under influence of afferent actions stipulated by the signal stimulus onset; the other one under the influence of afferentations complex from the motor response executive apparatus. The GP functioning "regime" is formed during the significance settling of the light stimulus trigger. Variations of VLs involvement in the system processes is determined by the possibility of reinforcement in the defensive behavior system.

Animals↗