title: A3 phenotype with A1 gene-specified enzyme character in serum.
abstract: We found an active A enzyme in the serum of A3 phenotype. The level of enzyme activity, pH optimum, Km and Vmax values, and heat stability were not different from those of A1 gene-specified enzyme. Red cell membrane from anti-A agglutinable cells showed weak A enzyme activity, whereas those from unagglutinable cells did not. From these results, it was assumed that the weak A expression in the present case is due to the suppression of A enzyme production only in hemopoietic tissues. This special A3 phenotype is highly accumulated in the Toyama district (frequency of approximately 0.00086).
authors.affiliation: Department of Legal Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Takizawa
authors.forename: K
authors.initials: K
authors.lastname: Nishino
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics* / Q000276:immunology; D004798:Enzymes / Q000097:blood / Q000235:genetics; D004910:Erythrocyte Membrane / Q000201:enzymology; D005260:Female; D014644:Genetic Variation; D006358:Hot Temperature; D006801:Humans; D007125:Immunogenetics; D007700:Kinetics; D008297:Male; D010375:Pedigree; D010641:Phenotype
chemical_list: D000017:ABO Blood-Group System; D004798:Enzymes