The Mz variety of the St(a+) phenotype--a variant of glycophorin A exhibiting a deletion.
The NeuNAc level of erythrocyte membranes from two related donors exhibiting the Mz variety of St(a+) phenotype within the MNSs blood group system was found to be decreased by about 16%. The quantity of glycophorin A was decreased by about 38%, whereas that of glycophorin B was not significantly different from normal. Mz erythrocyte membranes were also found to contain an abnormal component (molar ratio to glycophorin A about 0.89:1.0) with an apparent molecular mass of about 24,000 Da. Immunoblotting experiments and amino-acid sequence analysis revealed that the novel component (and glycophorin A in one of the donors) carries blood group M activity. Blood group N activity was demonstrable for glycophorin A and glycophorin B from both donors. Amino-acid sequence analysis of chymotryptic, tryptic and cyanogen bromide peptides demonstrated that the novel molecule exhibits the typical structure of a Sta-active molecule. However, since it exhibits blood group M activity, it appears to represent a variant of glycophorin A lacking the residues 27-58 (encoded by exon three of the glycophorin A gene) rather than a glycophorin B-glycophorin A-hybrid molecule of the anti-Lepore type. Since one of the Mz heterozygotes was found to exhibit both M- and N activity on glycophorin A, the Mz gene complex appears to encode a blood group N-active glycophorin A apart from the novel component and a blood group s-active glycophorin B, although the level of glycophorin A in the erythrocyte membranes is decreased by about half.(ABSTRACT TRUNCATED AT 250 WORDS)
Dahr
W
W
Centre Régional de Transfusion Sanguine de Nantes.
Blanchard
D
D
Chevalier
C
C
Cartron
J P
JP
Beyreuther
K
K
Fournet
B
B
D000595:Amino Acid Sequence; D000941:Antigens / Q000276:immunology; D004586:Electrophoresis; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology / Q000502:physiology; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D006021:Glycophorins / Q000235:genetics* / Q000302:isolation & purification; D006579:Heterozygote; D006801:Humans; D008951:MNSs Blood-Group System / Q000235:genetics; D008969:Molecular Sequence Data; D009438:Neuraminic Acids / Q000378:metabolism; D010641:Phenotype; D012795:Sialoglycoproteins / Q000235:genetics*
D000941:Antigens; D006021:Glycophorins; D008951:MNSs Blood-Group System; D009438:Neuraminic Acids; D012795:Sialoglycoproteins