title: Pj variant, a new hybrid MNSs glycoprotein of the human red-cell membrane.
abstract: An unusual glycoprotein variant (Pj) was found inherited through a caucasian family exhibiting atypical N and Nvg blood-group reactivities. Pj erythrocytes are blood-group-MS homozygous and have a normal sialic acid content. On sodium dodecyl sulphate/polyacrylamide-gel electrophoresis the variant contains a new component Pj of 24kDa apparent molecular mass in the monomeric state which is sharply stained by periodic acid/Schiff reagent. Both blood-group-MN (alpha) and -Ss (delta) glycoproteins were present. Homodimers (Pj2) as well as heterodimers with MN-glycoprotein (alpha Pj) and the Ss-glycoprotein (delta Pj) were also identified. The new sialoglycoprotein Pj is trypsin- and chymotrypsin-resistant in situ and carries N- and Nvg- but not M- and S-reactivities. The Pj component is labelled by lactoperoxidase-catalysed radioiodination. A 3H label is also easily introduced into the sialic acid or the galactose and galactosamine of the Pj glycoprotein. It is proposed that the Pj is a hybrid glycoprotein containing the N-terminal end of delta-glycoprotein and the C-terminal end of the alpha-glycoprotein. This proposal is supported by the finding that Pj carries a leucine residue at its N-terminus and is not immunoprecipitated by a monoclonal mouse antibody (R18) reacting specifically with the external domain of glycoprotein alpha. The red cells from the proposita Pj were found positive for a very low frequency MN antigen named Sta.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis* / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000097:blood* / Q000235:genetics; D006801:Humans; D007457:Iodine Radioisotopes; D007784:Lactoperoxidase / Q000378:metabolism; D010375:Pedigree; D014316:Tritium
chemical_list: D000596:Amino Acids; D001798:Blood Proteins; D006023:Glycoproteins; D007457:Iodine Radioisotopes; D014316:Tritium; D007784:Lactoperoxidase; D010450:Endopeptidases