Disease relevance of GYPB

• The isolated vesicles maintain their cytoplasmic integrity and normal membrane orientation, and are resistant to hemolysis over the pH range 5.0 - 11.0 and temperature range 4-50 degrees C. The only membrane proteins detected in vesicles from human erythrocytes were band 3 region polypeptides and bands PAS-1, PAS-2 and PAS-3 [1].
• Purified cDNAs and RNAs isolated from peripheral blood and erythroleukemia cell lines, HEL and K562, were used to develop an RT-PCR technique for amplifying GPA gene transcripts (GYPA) [2].
• To evaluate the clinical significance of antibodies to native or denatured (anti-n or anti-d) 60- or 52-kd Ro/SS-A proteins (60K or 52K) in Sjögren's syndrome (SS) [3].
• Serologic abnormalities and salivary gland dysfunction were associated with anti-n-60K in SS, whereas Hashimoto's thyroiditis in SS was related to anti-d-60K [3].
• We review the results obtained in the Milan hypertensive strain of rats (MHS) and in its appropriate control normotensive strain (MNS) to illustrate our approach to defining the role of cation transport abnormality in a type of genetic hypertension [4].

Psychiatry related information on GYPB

• There was no evidence of linkage of Alzheimer's disease with any of 27 phenotypic gene markers analyzed, but close linkage for the Rh and MNS blood group loci was excluded [5].

High impact information on GYPB

• Mutations that impair the -75 GATA-1 binding result in extinction of the -95 GPB construct activity if the -75 ubiquitous binding site is not altered, or in loss of erythroid specificity if the -75 ubiquitous binding site is also mutated [6].
• Analysis of the Alu sequence and flanking direct repeat sequences suggested that the GPA gene most closely resembles the ancestral gene, whereas the GPB and GPE genes arose by homologous recombination within the Alu sequence, acquiring 3' sequences from an unrelated precursor genomic segment [7].
• Further duplication and divergence of this gene yielded the GPB and GPE genes [7].
• Downstream from the Alu sequence, the nucleotide sequence of the precursor genomic segment is almost identical to that of the GPB or GPE gene [7].
• A human genomic library was screened by using the sequence of the 3' region of the GPB gene as a probe [7].

Biological context of GYPB

• DISCUSSION: The S-s-U+var phenotype arises from changes in or around GYPB exon 5 [8].
• These sequences include a region downstream of an Alu repeat sequence, which has been suggested to be a site for homologous recombination in the GPB gene during or after gene duplication [9].
• However, the predicted GPE amino acid sequence specifies blood group M, in contrast to GPB which carries blood group N [9].
• Encompassing exon 2, there were identical sequences stretches of 139 and 138 base pairs between GPAM and GPE genes and between GPAN and GPB genes, respectively [10].
• GYPB, the gene encoding the GPB protein, was cloned and sequenced after reverse transcription PCR amplification of total RNA isolated from ES [11].

Anatomical context of GYPB

• M and N blood group antigens are presented by glycophorins A (GPA) and B (GPB) of the erythrocyte membrane [10].
• Analysis of chimerism in immature (glycophorin A-positive [GYPA(+)], CD71(hi)) and mature (GYPA(+), CD71(neg)) erythroblasts confirmed the intramedullary loss of SS erythroblasts with progressive maturation [12].
• As a preliminary approach to the molecular analysis of this variant the restriction maps of the GPA and GPB genes were established by Southern blot analysis of genomic DNA and from genomic clones isolated from a human leukocyte library constructed in lambda EMBL4 [13].
• Glycophorin B (GPB) is an abundant cell surface glycoprotein which is only expressed in human erythroid cells [14].
• The differences in volume, sodium content, and Na+-K+ cotransport between erythrocytes of the two strains persisted after transplantation of bone marrow to irradiated F1 (MHS X MNS) hybrids [4].

Associations of GYPB with chemical compounds

• The Ux polymorphism, defined by a scarce serum (anti-Ux) directed against receptors within the homologous domains of the two glycoproteins, appears to be caused by differences in the Ss glycoprotein content between SS, Ss and ss red cells, rather than by an additional structural polymorphism on the Ss glycoprotein [15].
• Analysis of the difference by means of polyacrylamide gel electrophoresis in 1% sodium dodecyl sulphate and PAS staining failed to reveal significant variations in mobility and relative staining intensity of the main glycoprotein components, PAS-1, PAS-2 and PAS-3 [16].
• One of the zones in deoxycholate gel electrophoresis contains component PAS-3, and this glycoprotein seems to exist as a monomer in deoxycholate, but aggregates partially upon addition of dodecyl sulfate [17].
• This procedure consists of selectively blocking GPA-GPB heterodimer formation by selective modification of Cysteine 50 of GPB before RPLC [18].
• CONCLUSION: The Vr antigen arises from a point mutation 197C-->A on GYPA which is predicted to change serine at position 47 to tyrosine [19].

Regulatory relationships of GYPB

• Glycophorins A (GPA) and B (GPB) are specifically expressed in human erythrocytes and express MN and Ss blood group antigens [20].

Other interactions of GYPB

• GPA transcripts were very stable (at least 24 h), whereas GPB transcripts were severely reduced after 17 h [21].
• Close linkage to FY and SS (GYPB) was excluded for all chosen phenotypic models and to ACP1 and ADA for broader phenotypic models [22].
• GPA expresses M or N blood group antigen depending on the allelic gene (GPAM gene or GPAN gene), while GPB expresses only the N antigen [10].
• STUDY DESIGN AND METHODS: Taking advantage of the differences between the GPA and GPB genes, a polymerase chain reaction-based method was developed to detect all the Miltenberger glycophorin variants and St(a) subtype [23].
• Rh (Rhesus) proteins (D, CcEe) are expressed in red cells (RBC) in association with other membrane proteins (RhAG, LW, CD47 and GPB) [24].

Analytical, diagnostic and therapeutic context of GYPB

• MATERIALS AND METHODS: Following RT-PCR amplification of total RNA isolated from one Vr+ person (G488) and one Mt(a+) person (GH), the genes encoding glycophorin A (GYPA) and glycophorin B (GYPB) were cloned and sequenced [19].
• Northern blot analysis demonstrated that this novel glycophorin gene is expressed in an erythroid-specific manner and coordinately down-regulated together with GPA and GPB genes by a tumor-promoting phorbol ester [9].
• The precise locations of exon 1 and the exon encoding the transmembrane (TM) domain in GPA, GPB and GPE were then determined by hybridization with specific probes after restricted DNA fragments were separated by pulsed-field gel electrophoresis [25].
• In this homologous part of the genes, GPB lacks one exon due to a point mutation at the 5' splicing site of the third intron, which inactivates the 5' cleavage event of splicing and leads to ligation of the second to the fourth exon [26].
• Southern blot analysis of total genomic DNA revealed that the 5' half of the MiV* gene derived from glycophorin A (GPA) gene whereas the 3' half derived from glycophorin B (GPB) gene [27].

References