Assay of α-TV-Acetylgalactosaminyltransferases in Human Sera

Abstract

The study of the α-N-acetylgalactosaminyltransferase in the sera of 19 individuals belonging to the rare A(m) blood group makes it possible to confirm the heterogeneity of this phenotype established on genetical and immunological criteria. Two groups of subjects, A(m) and A(y), can be distinguished. For the individuals of the first group, named A(m), 15 samples (7 families) have been studied, the phenotype is inherited as an allele at the ABO locus. 14 of these subjects, have an α-N-acetylgalactosaminyltransferase whose kinetic properties were similar to those of A(1) subjects. In one family, however, the A transferase detected is of the A(2) type. On a quantitative level, the enzyme activities of these sera only reached 30-50% of the average value observed for A(1) or A(2) subjects, respectively. These facts suggest the existence of a genetic inhibitor, possibly linked to the ABO locus, preventing either an A(1) or A(2) gene from acting at the level of some cellular lines and leading therefore to the recognition of phenotypes named A(m)^A1 and A(m)^A2. On the contrary, under the experimental conditions used, no α-N-acetylgalactosaminyltransferase activity was detected among the four individuals of the second group, named Ay by Weiner et al. [37], and whose appeareance in siblings results from the action of a recessive modifying y^A gene.

Weak A Phenotypes Possibly Caused by Mutation1

“…(4) Absence of the A transferase activity in the sera of members of the L. family with postulated A, phenotypes is in agreement with earlier data of Curtron et al [8].…”

Weak A Phenotypes Possibly Caused by Mutation

“…The H transferase activities in their serums were within the normal range. (4) Absence of the A transferase activity in the sera of members of the L. family with postulated Ay phenotypes is in agreement with earlier data of Cartron et al [8], Subsequently, however, employing prolonged incubation times, Cartron [9] reported very weak A transferase activ ities ranging from '/so to V200 of control samples in 4 unrelated Ai individuals. Initially, we have also reported very weak A transferase activities in the sera of the mem bers of the L. family with weak A phenotypes [10].…”

Activity of 2‐α‐L‐fucosyltransferase in human sera and red cell membranes A study of common ABH blood donors, rare ‘Bombay’ and ‘Parabombay’ individuals

“…Enzyme assays in human sera: A and B enzyme assays have been described [28,29]. H enzyme assays were carried out in total vol.…”