抄録
Three related forms of phenol sulfotransferase, thermostable ST1A2 and ST1A3 and a thermolabile ST1A5 are known to exist in human livers. Thermostable forms, whose activities are polymorphically distributed in human tissues, have been shown to mediate the bioactivation of carcinogenic N-hydroxy aromatic amines as well as phenolic substrates. Variant forms of ST1A3 mRNAs (i.e. Arg213His and Met223Val) have been found in human livers. In a Japanese population, allele frequencies of 213Arg and 213His were 0.83 and 0.17, respectively. No remarkable difference in [35S]3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent sulfation of p-nitrophenol was observed between recombinant 213Arg- and 213His-type ST1A3, although it was reported that 213His homozygosity was associated with both lower (less than one-sevenths) p-nitrophenol sulfation and thermolability in human platelets. The recombinant ST1A3 (213His) did exhibit unstability at 45° and 37°C as compared with ST1A3 (213Arg). Liver cytosols from 213His homozygotes did not always show low p-nitrophenol-sulfating activities. Different molecular mechanisms in sulfation polymorphism are suggested in livers and platelets of humans.
