Biomedical subjects

Marion E Reid

Publications and source records attributed to Marion E Reid.

At least 19 recordsLinked to original sources

PubMed2006

Molecular basis of two novel high-prevalence antigens in the Kell blood group system, KALT and KTIM.

BACKGROUND: The Kell blood group system consists of 25 antigens that result from single-nucleotide polymorphisms. Most polymorphic Kell antigens reside on the N-terminal domain of Kell before the zinc-binding catalytic motif, which is the major site for endothelin-3-converting enzyme activity. Kell antigens are important in transfusion medicine owing to their strong immunogenicity, and the corresponding antibodies are clinically significant. Two probands were studied whose serum samples contained antibodies to different high-prevalence Kell antigens. STUDY DESIGN AND METHODS: Standard hemagglutination methods were used for serologic testing of Proband 1 and Proband 2. DNA was prepared from both probands and family members. The 19 exons and the intron-exon regions of KEL from both probands were amplified by polymerase chain reaction, and the sequences were compared with that of common KEL. The identified substitutions were located on a three-dimensional model of Kell generated based on the crystal structure of neutral endopeptidase, a homolog of Kell. RESULTS: In Proband 1, a homozygous 1988G>A mutation (Arg623Lys) in Exon 17 was present. One sibling of Proband 1 was homozygous for 1988G>A. In Proband 2, a homozygous 1033G>A mutation (Asp305Asn) in Exon 8 was present. Three siblings of Proband 2 were heterozygous for 1033G>A. CONCLUSION: The identified KEL mutations of the two probands are novel and inherited. The antigen absent from the red blood cells (RBCs) of Probands 1 and 2 are named KALT and KTIM, respectively. KALT is unique in that it is the only Kell antigen sensitive to treatment of RBCs by trypsin.

Amino Acid Substitution↗

PubMed2006

The production of red blood cell alloantibodies in mice transfused with blood from transgenic Fyb-expressing mice.

BACKGROUND: A murine model would be useful to identify which immune mechanisms could be manipulated to treat or prevent red blood cell (RBC) alloimmunization in patients who become sensitized to multiple or widely expressed antigens. STUDY DESIGN AND METHODS: Transgenic mice (B6CBAF1/J-Tg-Fy(b)) expressing the human Fy(b) antigen of the Duffy (Fy) blood group were donors. Recipient B6CBA-F1 mice received four weekly intravenous (IV) transfusions: either 0.3 mL of washed buffy coat-depleted RBCs or 0.3 mL of RBCs with spleen cells. Titers of immunoglobulin M (IgM) and immunoglobulin G (IgG) were measured in recipient serum samples by flow cytometry with RBCs from donor mice as target cells. Recipient serum samples were also tested against human RBCs of various Fy phenotypes. Additionally, RBC survival studies were performed in alloimmunized mice utilizing biotin-labeled Fy(b) transgenic mouse RBCs. RESULTS: B6CBA-F1 mice receiving washed buffy coat-depleted RBCs first made IgM, followed by IgG alloantibodies to transgenic mouse Fy(b)-positive RBCs. Recipients of Fy(b)-positive RBCs mixed with spleen cells also produced IgM and IgG alloantibodies, but at a slower rate than recipients of washed buffy coat-depleted RBCs. Serum samples showed specificity for Fy3, Fy(b), and Fy6. Decreased survival of transfused RBCs was evident at 24 hours after transfusion. CONCLUSIONS: It is possible to elicit the formation of anti-Fy alloantibodies by IV transfusion in mice that lack Fy antigens. The transfusion of RBCs alone was adequate to stimulate alloantibody production in B6CBA-F1 recipient mice. The survival of transfused Fy(b)-positive RBCs is diminished in sensitized mice. This model will be useful in further studies of RBC alloimmunization.

Animals↗

PubMed2006

Analysis in non-human primates reveals that the ancestral Band 3 gene encodes Dib and the Band 3-Memphis phenotype.

BACKGROUND: The anion exchanger, Band 3, carries antigens in the Diego blood group system, and can carry the Band 3-Memphis phenotype. Although Di(b) is of high prevalence and Band 3-Memphis is of low prevalence in humans, it has been suggested that both are on the ancestral gene. We determined the orthologue nucleotide sequences corresponding to these two polymorphic sites, Di(a)/Di(b) (2561T > C; Leu854Pro) and Band 3-Memphis(166A > G; Lys56Glu) in several nonhuman primates. METHODS: Genomic DNA was extracted from blood samples of great apes, lesser apes, old world monkeys, new world monkeys and prosimians. PCR amplifications were done with primer pairs that were located in the flanking intronic regions of Exon 4 and Exon 19; and the amplified products were sequenced. RESULTS: Amino acid sequence alignment of nonhuman primates band 3 with that of human showed extensive homologies. In exon 4, Glu56Lys polymorphic site showed Glu similar to Band 3-Memphis type and in exon 19, Leu854Pro polymorphic site showed Pro indicating Di(b) phenotype. CONCLUSIONS: The nonhuman primates have nucleotide sequences of Di(b)(2561C) in cis to Band 3-Memphis (166G), which is consistent with the assertion that the Di(b) and Band 3-Memphis phenotype represents the ancestral Band 3 gene.

Amino Acid Sequence↗

PubMed2005

A panel of monoclonal antibodies recognizing GPI-anchored ADP-ribosyltransferase ART4, the carrier of the Dombrock blood group antigens.

ART4 (CD297) is a member of the family of toxin-related ADP-ribosyltransferases (ARTs) and is the carrier of the Dombrock blood group alloantigens (Do). Two mouse monoclonal antibodies (MIMA-52 and MIMA-53), and two rat monoclonal antibodies (N0NI-B4 and NONI-B63) were obtained following immunization of mice with human Do/ART4-transfected cells and of rats with human Do/ART4 cDNA, respectively. All four mAbs recognize Do/ART4-transfected Jurkat cells but not untransfected cells by FACS analysis. Staining of Do/ART4-transfected cells by these mAbs was reduced following treatment of cells with PI-PLC, confirming that Do/ART4 is anchored in the cell membrane by linkage to glycosylphosphatidylinositol as predicted from its amino acid sequence. The four mAbs did not react with Gy(a-) (Dombrock null) erythrocytes but agglutinated other red blood cells. By flow cytometric analysis, all mAbs reacted prominently with erythrocytes, and weakly with peripheral blood monocytes and splenic macrophages, but not with B-lymphocytes or T-lymphocytes. The mAbs reacted weakly also with human umbilical vein endothelial cells and the basophilic leukemia KU-812. Immunohistology revealed staining of epithelia and endothelia on sections of tonsils. In FACS analyses NONI-B4 competed with MIMA-52 for binding to Do/ART4-transfected cells and erythrocytes, whereas NONI-B63 competed with MIMA-53. Neither of the mAbs reacted with mouse ART4-transfected cells, but NONI-B63 and MIMA-53 did react with a mouse/human ART4 chimera, indicating that the epitope recognized by these mAbs lies in the C-terminal half of the protein.

ADP Ribose Transferases↗

PubMed2005

Human blood group genes 2004: chromosomal locations and cloning strategies.

Of the 29 human blood group system genes, 27 have been localized to 14 autosomes and 2 have been assigned to the X chromosome. It is remarkable that 28 of the 29 system genes have now been localized to a single cytogenetic band on a specific chromosome. In this review, we summarize the chromosomal locations and cloning strategies used for those genes encoding blood group systems. We highlight such information about the 3 most recently defined blood group systems (I, GLOB, and GIL). In addition, we provide new information about 2 older blood group systems (SC and RAPH) whose polymorphisms have been defined in cloned genes.

Blood Group Antigens↗

PubMed2005

STAR: a novel high-prevalence antigen in the Scianna blood group system.

BACKGROUND: More than 20 years ago, a proband was described whose red blood cells (RBCs) typed Sc:1,-2,3. His serum sample contained an immunoglobulin G alloantibody that reacted with all RBCs tested except his own, his brother's, and those with the Sc:-1,-2 phenotype. Cloning of the SC gene allowed determination of the molecular basis associated with this novel high-prevalence antigen. STUDY DESIGN AND METHODS: Samples from frozen storage were obtained from the proband, his serologically matched brother, and 15 serologically mismatched family members. DNA was extracted, and amplified products from all 11 SC (ERMAP) exons and their flanking regions of the proband were sequenced. RESULTS: A single-nucleotide mutation was detected (139G>A) in Exon 3 that is predicted to encode a change of Amino Acid 47 from glutamic acid to lysine. The sequence analyses on samples from family members were as expected. CONCLUSIONS: The absence of the high-prevalence antigen STAR detected by the proband's antibody is likely associated with lysine at Position 47 of the Sc glycoprotein. This amino acid change is located on the extracellular portion of HERMAP, 10 residues upstream from the polymorphism associated with Sc1 and Sc2 (Gly57Arg). STAR expands the Sc blood group system to five antigens and has been assigned the ISBT Number 013005 (SC5).

Antigens, Surface↗

PubMed2005

Complexities of the Dombrock blood group system revealed.

The Do(a) antigen was discovered after I began my career in immunohematology and I have been fortunate to be involved in several fascinating discoveries in the Dombrock blood group system. The Do(a) antigen and its antithetical antigen, Do(b), have a prevalence that makes them useful as genetic markers. The paucity of reliable anti-Do(a) and anti-Do(b) has prevented this potential from being realized; however, our ability to type for DO alleles at the DNA level has made it possible to test cohorts from different populations. In 1992, the Dombrock blood group system was expanded to include three phenotypically related antigens, Gy(a), Hy, and Jo(a), when it was discovered that the Gy(a-) phenotype was the null of the Dombrock system. Based on the knowledge that the Dombrock glycoprotein is attached to the RBC membrane via a glycosylphosphatidylinositol linkage and subsequent to the assignment of the corresponding gene to the short arm of chromosome 12, expressed sequence tags from terminally differentiating human erythroid cells were analyzed in silico to identify the DO gene. This allowed determination of the molecular basis of the various Do phenotypes and the realization that DO is identical to the gene encoding a mono-ADP-ribosyltransferase, ART4. No enzymatic activity in RBCs has been demonstrated and the function of this glycoprotein, on the outside surface of RBCs, has yet to be determined. This review is a synthesis of our current knowledge of the Dombrock blood group system.

Blood Group Antigens↗

PubMed2005

SCER and SCAN: two novel high-prevalence antigens in the Scianna blood group system.

BACKGROUND: More than 20 years ago, two probands were described whose red blood cells (RBCs) typed Sc:1,-2,3. Their serum samples contained alloantibodies reactive with all RBCs tested except those of the Sc:-1,-2,-3 phenotype. Cloning of the Scianna gene allowed us to determine the molecular bases of these samples. STUDY DESIGN AND METHODS: In a collaborative effort, the two probands' samples and also two Sc:-1,-2,-3 samples were obtained from frozen storage. All 11 SC (ERMAP) exons and their flanking regions were sequenced. RESULTS: The two probands with antibodies to Scianna-related antigens were homozygous, respectively, for an ERMAP(R81Q) allele caused by a G to A substitution at nucleotide 242 in the ERMAP gene and for an ERMAP(H26Y,G35S) allele, in which the G35S substitution was caused by a G to A substitution at nucleotide 103. Two patients with the Sc:-1,-2,-3 phenotype both carried ERMAP(R332X) alleles caused by a C to T substitution at nucleotide 994 that differed at one nucleotide position in the noncoding region of exon 11. In eight samples carrying orphan low-prevalence antigens, no ERMAP variants were detected that could be implicated in Scianna antigen expression. CONCLUSION: SCER and SCAN expanded the Scianna blood group system to seven antigens, have been assigned the ISBT numbers 013.006 (Sc6) and 013.007 (Sc7), and were associated with ERMAP(R81Q) and ERMAP(G35S) proteins, respectively. ERMAP(R332X) is a second molecular basis for the Sc(null) phenotype. The eight low-prevalence antigens By, To(a), Pt(a), Re(a), Je(a), Li(a), SARA, and Sk(a) do not belong to the Scianna blood group system.

Alleles↗

PubMed2005

A flexible array format for large-scale, rapid blood group DNA typing.

BACKGROUND: Typing for blood group antigens is currently performed by hemagglutination. The necessary reagents are becoming costly and limited in availability, and the methods are labor-intensive. The purpose of this study was to determine the feasibility of the use of large-scale DNA analysis in a microarray as a substitute for blood group typing. STUDY DESIGN AND METHODS: DNA, extracted from blood samples that had been phenotyped for some of the red blood cell antigens, was analyzed for selected blood group alleles by bead array (BeadChip, (BioArray Solutions Ltd., Warren, NJ) Illumina) [corrected] and by manual polymerase chain reaction (PCR)-based assays. Selected alleles were identified by enzyme-mediated elongation of probes, which were on color-encoded beads assembled into arrays on silicon chips. The performance of a prototype BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] (BLOOD-1) containing single-nucleotide polymorphisms (SNPs) for FYA/B, FY-GATA, DOA/B, COA/B, LWA/B, DIA/B, and SC1/SC2 was verified with DNA from serologically characterized donors. It was then used to analyze more than 400 samples of partially defined phenotype. Samples from Chinese, Ashkenazi, and Thai donors (total n = 227) were tested with BLOOD-1. An expanded BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] with a total of 18 SNPs (36 alleles; SNPs in BLOOD-1 and M/N, S/s, Lu(a)/Lu(b), K/k, FY265[for the Fy(X) polymorphism], Jk(a)/Jk(b), DO323[for Hy], DO350[for Jo(a)], and HgbS) was then evaluated with a subset of previously tested samples from Chinese, Ashkenazi, and New York blood donors (127) and an additional set of samples from Israeli donors (total n = 188). RESULTS: Results obtained by BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] analysis were concordant with those obtained with the manual PCR-restriction fragment length polymorphism, allele-specific PCR, and hemagglutination assays. The frequencies of the alleles in the samples from different ethnic panels were within the expected ranges; however, two new DO alleles were discovered. CONCLUSION: It has been shown that microarray technology can be used to type DNA and detect new alleles in donor cohorts.

Alleles↗

PubMed2004

The Fya, Fy6 and Fy3 epitopes of the Duffy blood group system recognized by new monoclonal antibodies: identification of a linear Fy3 epitope.

Four new anti-Duffy murine monoclonal antibodies (MAbs): two anti-Fy6 (MIMA-107 and MIMA-108), one anti-Fya (MIMA-19) and one anti-Fy3 (MIMA-29) were characterized. Identification of epitopes by means of synthetic peptides (Pepscan) showed that the anti-Fy6 reacted most strongly with peptides containing the sequence 19QLDFEDV25 of the Duffy glycoprotein, and less strongly with peptides containing LDFEDV (MIMA-107) or LDF only (MIMA-108). The anti-Fya recognized epitope 38DGDYGA43 containing the Gly42 residue, which defines the Fya blood group antigen. MIMA-29 is the first anti-Fy3 reactive with a linear epitope 281ALDLL285 located in the fourth extracellular domain (ECD4, loop 3) of the Duffy glycoprotein. The four new antibodies extend the list of six anti-Fy MAbs formerly characterized by Pepscan analysis that allow some general conclusions. Fine specificities of various anti-Fya, or anti-Fy6 are not identical, but all of them recognize linear epitopes located around, respectively, Gly42 or between two potential N-glycosylation sites at Asn16 and Asn27. Anti-Fy3 recognize either a linear epitope located in ECD4, or a conformational epitope that includes amino acid residues of ECD4 and of other ECDs.

Animals↗

PubMed2004

Red blood cell blood group antigens: structure and function.

Red blood cell (RBC) blood group antigens are polymorphic, inherited, carbohydrate or protein structures located on the extracellular surface of the RBC membrane. They contribute to the architecture of the RBC membrane, and their individual function(s) are being slowly revealed. The biological qualities assigned to these RBC membrane structures are based on observed physiological alteration in RBCs that lack the component, by documenting similarities in its protein sequence (predicted from the nucleotide sequence of the gene) to proteins of known function and by extrapolation to identified functional homologues in other cells. The varied roles of RBC antigens include membrane structural integrity, the transport of molecules through the membrane, as receptors for extracellular ligands, adhesion molecules, enzymes, complement components and regulators, and in glycocalyx formation.

Blood Group Antigens↗

PubMed2004

Intravenous (IV) anti-D and IV immunoglobulin achieve acute platelet increases by different mechanisms: modulation of cytokine and platelet responses to IV anti-D by FcgammaRIIa and FcgammaRIIIa polymorphisms.

Intravenous (IV) anti-D and IV immunoglobulin (IVIG) slow the Fcgamma receptor (FcgammaR)-mediated destruction of antibody-coated platelets in patients with immune thrombocytopenic purpura (ITP). This pilot study explored the mechanism of these immunoglobulin preparations by measuring interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1), IL-6 and tumour necrosis factor alpha (TNFalpha), before and after infusion and by assessing the effect of FcgammaRIIa and FcgammaRIIIa polymorphisms on both cytokine and haematologic responses to anti-D. Following IVIG, only IL-10 was increased at 2 h and MCP-1 on day 7 (P < 0.05). In contrast, 2 h after anti-D infusion, plasma levels of all four cytokines were increased (P < 0.01); five of six patients with the highest MCP-1, IL-6 and TNFalpha levels had chills. Higher IL-10 levels correlated with platelet increases at 24 h and haemoglobin decreases at day 7 (P < 0.025). Patients with the FcgammaRIIa-131HH genotype had significantly higher MCP-1, IL-6 and TNFalpha levels. Patients with the FcgammaRIIIa-158VF genotype had higher platelet increments at day 7 (P < 0.05). Soluble CD16 (sCD16) was increased 2 h after IV anti-D; day 7 levels correlated with day 7 haemoglobin decreases (P < 0.01). In conclusion, the relationship of FcgammaRIIa and FcgammaRIIIa polymorphisms with both cytokine levels and platelet increments implicated these receptors in responses to anti-D and supported different mechanisms of FcgammaR interaction to those seen with IVIG.

Adolescent↗

PubMed2004

Recombinant glycophorins C and D as tools for studying Gerbich blood group antigens.

BACKGROUND: The Gerbich blood group system antigens are carried on glycophorin C (GPC) and glycophorin D (GPD) and variants thereof. These glycoproteins have been expressed in a heterologous system to study the individual antigens and to determine whether Ana is antithetical to Ge2. STUDY DESIGN AND METHODS: cDNAs encoding GPC, GPD, GPC.Yus, GPC.Ge, GPC.Lsa, and GPD.Lsa were transfected and stably expressed in a human embryonic kidney cell line (293T). Individual Gerbich antigens were analyzed with MoAbs and human polyclonal antibodies by flow cytometry and immunoblotting. Recombinant GPD and GPD.Ana were expressed transiently and analyzed for expression of Ge2 and Ana antigens. RESULTS: All recombinant variants were detected with sialidase-resistant and -sensitive anti-Ge2, anti-Ge3, and anti-Ge4. Ge4 antigen expression was depressed in GPC.Ls(a) transfectants as well as on Ls(a+) RBCs. GPD.An(a) recombinant protein expressed Ana and Ge2 antigens. CONCLUSION: Cell lines stably expressing glycosylated Gerbich proteins were developed in a heterologous system by transfecting individual variant forms of GPC and GPD. Unexpectedly, it was found that Ge4 antigen is reduced in both the GPC.Ls(a) recombinant and the Ls(a+) RBCs. It was also shown that Ana and Ge2 antigens were expressed on a single GPD.An(a) protein and, therefore, they cannot be antithetical.

Antibodies, Monoclonal↗

PubMed2004

Evidence that Hy- RBCs express weak Joa antigen.

BACKGROUND: RBCs of the Hy- phenotype have, in the past, been typed as Gy(a+w), Hy-, Jo(a-), and RBCs with the Jo(a-) phenotype type Gy(a+), Hy+w, and Jo(a-). Anti-Hy and anti-Joa are difficult to identify mainly because appropriate reagent RBCs are poorly characterized. Historically, anti-Joa has not reacted with RBCs with either phenotype. This report describes a case of an anti-Joa that shows Hy- RBCs express some Joa antigen, albeit weakly. CASE REPORT: Anti-Joa was identified in a serum sample of a 71-year-old woman. The antibody reacted 1+ to 2+ by the IAT with all untreated and ficin-treated panel RBCs and did not react with Gy(a-) RBCs and Jo(a-) RBCs. Unexpectedly, the serum sample reacted weakly with six of eight RBC samples with the Hy- phenotype. The anti-Joa was adsorbed onto and eluted from Hy- RBCs, indicating the presence of weak Joa antigen. The patient's RBCs typed Gy(a+), Hy+, Jo(a-). DNA studies using PCR-RFLP analysis showed the patient to be homozygous for the JO allele, which is consistent with the serologically determined Jo(a-) status. CONCLUSION: The DNA and serologic evidence of this case show that Hy- RBCs may express low levels of Joa antigen, which contradicts previously published data concerning the Joa type of Hy- RBCs.

Aged↗

PubMed2004

Substitution Glu480Lys in erythroid band 3 corresponds to the Fr(a) blood group antigen and supports existence of the second ectoplasmic loop of band 3.

BACKGROUND: Polymorphisms in extracellular loops of RBC band 3 correspond to antigens of the Diego blood group system. Of the seven putative extracellular loops, no mutations have until recently been found in the second, fifth, and sixth loops. We detected a substitution Glu480Lys that would be located in its second ectoplasmic loop. We hypothesized the substitution may underlie a novel antigen of the Diego system. STUDY DESIGN AND METHODS: IAT was performed using two different multispecific sera containing anti-Fr(a) and a series of multispecific sera containing antibodies against other blood group antigens of the Diego blood group system but not agglutinating Fr(a+) RBCs. Biosynthesis of band 3 was studied by RT-PCR of reticulocyte RNA and electrophoresis of solubilized RBC membranes. Anion exchange function of band 3 was studied by measuring the influx of radiolabeled sulfate. RESULTS: RBCs from the Glu480Lys carrier were agglutinated with sera containing anti-Fr(a) and not by sera with specificities for other antigens of the Diego system. We detected identical quantities of mRNA corresponding to the two band-3 alleles and normal content of band 3 in the RBC membranes, as well as normal sulfate influx into RBCs from the Fr(a) heterozygote. CONCLUSIONS: We confirmed the previously reported molecular basis of the Fr(a) antigen, thus providing supportive evidence for the existence of the second extracellular loop of band 3. We also demonstrated that this substitution does not affect mRNA stability, surface expression, and anion exchange function of band 3.

Amino Acid Sequence↗

PubMed2004

A new hybrid RHCE gene (CeNR) is responsible for expression of a novel antigen.

BACKGROUND: The red blood cells (RBCs) of a patient, known to have the probable DC(W)(e)/D-- phenotype, typed as D(W)- and Rh32- but were unexpectedly agglutinated by an anti-D(W)/Rh32 serum. The reactivity suggested that the RBCs carried a novel antigen and that the molecular background of this DC(W)(e)/D-- phenotype might be different from those reported. The purpose of this study was to determine the molecular basis of the Rh phenotype. STUDY DESIGN AND METHODS: Samples were obtained for family studies. Standard hemagglutination methods were used. RH mRNA transcripts were isolated by reverse transcription-polymerase chain reaction and sequenced. RESULTS: Sequence analysis revealed that the probond had three different RH transcripts: a normal RHD and two different hybrid transcripts from the RHCE locus, a RHCE-D hybrid with exon 1 from RHCE associated with the D-- haplotype, and a new RHCE-D hybrid. In this new hybrid, exons 1 to 5 are RHCe-specific and exons 6 to 10 correspond to RHD. The C(W) antigen is also encoded by this hybrid gene. Family studies confirmed that the new RHCE-D hybrid is linked in cis to conventional RHD. CONCLUSION: A new RHCE-D structure is associated with altered expression of C and e antigens in this family and the generation of a novel low-prevalence antigen (CENR).

Amino Acid Sequence↗

PubMed2003

Erythrocyte detergent-resistant membrane proteins: their characterization and selective uptake during malarial infection.

Infection of human erythrocytes by the apicomplexan malaria parasite Plasmodium falciparum results in endovacuolar uptake of 4 host proteins that reside in erythrocyte detergent-resistant membranes (DRMs). Whether this vacuolar transport reflects selective uptake of host DRM proteins remains unknown. A further complication is that DRMs of vastly different protein and cholesterol contents have been isolated from erythrocytes. Here we show that isolated DRMs containing the highest cholesterol-to-protein ratio have low protein mass. Liquid chromatography, mass spectrometry, and antibody-based studies reveal that the major DRM proteins are band 3, flotillin-1 and -2, peroxiredoxin-2, and stomatin. Band 3 and stomatin, which reflect the bulk mass of erythrocyte DRM proteins, and all tested non-DRM proteins are excluded from the vacuolar parasite. In contrast, flotillin-1 and -2 and 8 minor DRM proteins are recruited to the vacuole. These data suggest that DRM association is necessary but not sufficient for vacuolar recruitment and there is active, vacuolar uptake of a subset of host DRM proteins. Finally, the 10 internalized DRM proteins show varied lipid and peptidic anchors indicating that, contrary to the prevailing model of apicomplexan vacuole formation, DRM association, rather than lipid anchors, provides the preferred criteria for protein recruitment to the malarial vacuole.

Animals↗

PubMed2003

Mutations in GYPB exon 5 drive the S-s-U+(var) phenotype in persons of African descent: implications for transfusion.

BACKGROUND: The S-s-U- phenotype in African Americans is due to a GYPB deletion, however the molecular basis for the S-s-U+var phenotype is poorly understood. Variable reactivity of S-s-U+var RBCs with monoclonal anti-He or by anti-U has been demonstrated, however the underlying molecular bases for this phenotype remain to be established. STUDY DESIGN AND METHODS: Hemagglutination was performed on 104 S-s- blood samples using monoclonal anti-He and anti-U. GYPB was sequenced from selected samples. Allele and exon-specific PCR analysis was used to identify wild-type and mutant alleles. RESULTS: The RBCs of 49-percent S-s- samples were identified as S-s-U+var by hemagglutination. Sequencing analysis of 41 samples revealed 1) a point mutation at +5 (g > t) of intron 5 that resulted in skipping of exon 5 in 34 samples; 2) two mutations (208G > T and 230C > T) caused partial skipping of exon 5 in four samples due to activation of a cryptic 3' splice site that resulted from a C > G transversion at nt251 present in all GYPB*S alleles and most GYPB*s alleles tested. Three samples were heterozygous for the mutated alleles. DISCUSSION: The S-s-U+var phenotype arises from changes in or around GYPB exon 5. The weak expression of U and in most examples, He, may be due to low levels of normal transcription of the variant gene or to posttranscriptional down regulation.

Black or African American↗