Abnormal blood group galactosyltransferase in blood type A1B-subjects whose sera contain anti-B agglutinin

摘要

A blood type A1B female, whose plasma agglutinates B red blood cells from other subjects but not her own, was found. Her sister with blood type A1B (sister-1) exhibited the same peculiarity. The agglutination titer of red cells from these two subjects is lower than that of normal B. Her father is blood type B, and his plasma did not agglutinate B red cells from other subjects and his own. Her mother and another sister (sister-2) were usual blood type A1. Blood group galactosyltransferase (B-enzyme) activity of plasma from the propositus, sister-1, and their father was very low. Km for 2′-fucosyllactose of B-enzyme of these subjects was 1.3 mM, which was more than two times higher than that of the normal value. Km for UDP-Gal was similar, but the pH-activity profile differed for the two enzyme