Abstract
Glycophorins of erythrocytes of two unrelated individuals who exhibit the Dantu blood group phenotype were studied. Immunoblots indicated that erythrocytes of each individual contained a complement of a normal alpha-glycophorin (glycophorin A) and a variant N-glycophorin. delta-Glycophorin (glycophorin B) was present in one donor's cells but not the other's; the s and N phenotypes of the latter's erythrocytes may derive from the variant glycophorin. The variant glycophorin is of a smaller size, does not bind to Lens culinaris lectin agarose, and lacks residues approximately 40-60 of alpha-glycophorin and its single asparagine-linked carbohydrate; it contains approximately 2 less O-glycosidically bound units whose structures are identical to those found in alpha-glycophorins. All these properties are characteristic of delta-glycophorin. The variant is related to alpha-glycophorin in the carboxyl-terminal region as shown by reaction with a specific antiserum. Sequence analyses of a mixture of chymotryptic peptides of a CNBr fragment of the variant glycophorin identified the sequence Val-His-Arg-Phe-Thr-Val-Pro-Glu-Ile-Thr-Leu-Ile-Ile that contains the junction point of delta- and alpha-glycophorins spanning residues 33-38/39 of delta-glycophorin and residues 71/72-77 of alpha-glycophorin. Sequence analysis of a mixture of CNBr fragments allowed us to conclude that the variant originates from delta-s- rather than delta-S-glycophorin. The quantity of the variant Dantu glycophorin when compared to alpha-glycophorin differed in the two individuals, the ratio being 2/1 in one individual's cells and 0.5/1 in the other's. This may reflect that the two donors belong to different varieties of Dantu phenotypes. Together, the evidence indicates that both donors' erythrocytes contain a (delta-alpha) variant glycophorin, whose amino terminus originates from delta-s-glycophorin and the carboxyl end from alpha-glycophorin with a junction point around residues 39 of delta- and 71 of alpha-glycophorins. The results suggest that the unique junction region may be characteristic of the Dantu phenotype.
Highlights
Glycophorins of erythrocytes of two unrelated indi- glycoproteins whose predominant formspossess the antigens viduals who exhibitthe Dantublood group phenotype of the MNSs blood group system
The variant glycophoriins of a smaller size, does not bind to Lens culinaris lectin agarose, and lacks residues -40-60 of a-glycophorin and its single asparagine-linked carbohydrate; it contains-2 less O-glycosidically bound units whose structures areidentical to structures of the glycoproteins are well established, and differencesbetween the products of the respectivealleles are known; theM-andN-a-glycophorins differ in two amino acids within the amino-terminal pentapeptide; and Sth-eand s-6-glycophorinsdifferby methionine or threonine, respectively, occupying residue 29 of the polypeptide. 6-Glycophorins are identical to a-N-glycophorin within the first26 resithose found in a-glycophorinsA. ll these propertiesare dues, but they diverge in sequencewith few areas of characteristic of 6-glycophorin
Presence of a-Glycophorin and a Variant N-Glycophorin in Dantu Erythrocytes-Immunoblots of Dantu erythrocytes probed with antiglycophorin serum show the presence of aglycophorin (Fig. 2A, bands 1 and 5 ), 6-glycophorin,and glycophorins that exhibit a mobility identical to variant St"glycophorin [12]
Summary
Immunoblots indicatedthat erythrocytes (Glycophorins A) exhibit the antigensfor the M and N blood of each individual containeda complement of a normal groups and the mino6r-glycophorins (GlycophorinsB) specify a-glycophorin (glycophorin A) and a variant N-glyco- the S and s reactivities. The quantityof the variant Dantu glycophorin whefnrom the deletion of 6-glycophorin gene in individuals exhibcudw0teyor.oah5pTymln1oestooh,1spsgr.ertaseohirntbceeaheytdmerhltaoreeit,tnncsoitgooohoneatbtott-heaeegerivilnmnrdyi’dgicsifen.of2nuepT1crsh1aeehonoiiristnnir(mnivd&goaiaaicndrn)yaieiaerfttfeevtieeinfsaesrldrtseehiidfcavarotniotttdgfithhmbnulDeayoatctlat6’htohnsw-pestcuoh-tegwodlpllriooyshninncedoao,nirnpvoshdi-’do-rippotianytfnhhipIndooanegrraniia-cSnngions-lpnsadyor-nticefUavdvoiiei-anpdrobuehyvuldaotosahlrosreritidhonquaocsnudgmy(tiyr1mtooewN2uzos)epy-l.oSgapIfponrtr”ehuttqw-shesgueniolfsnaoyorntutcreeytnodpitprtphoieeeeherlv(staoi1oStdrf8eeitdn)”an.,cbiwnneltooedhtorihavmadatnitdagaailuslreyhaoMrzlyuyseb-ptdaerh-ipxrdggohhllociyeybfynccitoo6ote-----s and the carboxyl end from a-glycophorin wiathjunc- ing the Dantublood group phenotype and demonstrated that tion point around residues of 6- and 71 of a-glyco- their erythrocyte membranes contain a complement of phorins. F , ~1..pro bin sequence sofa-^-, o-N-, 6-S-, and 6-s-glycophorins; a"serine and -glycine, and a-N-leucine and -glutamic acid at residues a1tarnedsid5u,ere2s9peacntdiv6e-lSy;-m6-est-hthiorenoinneinaet that position (Refs. 4-6 and 8; modified from Ref. 32).Carbohydrate attachment sites of a-glycophorin are included. *, 0-glycosidically linked units; e
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