TRANSLATION INITIATION SITES AND RELATIVE ACTIVITY OF LARGE AND SMALLFORMS OF HUMAN CHOLINE-ACETYLTRANSFERASE

We have previously shown that translation of human choline acetyltrans ferase (ChAT) mRNA starts at least at two sites and produces two enzym e proteins with different molecular weights. In this study, translatio n initiation sites and relative activity of large and small forms of C hAT were determined by site-directed mutagenesis, followed by expressi on and immunoblotting analyses. The large and small forms were transla ted at the first and second ATG codons of ChAT cDNA, respectively, and the specific activity was almost the same between the two forms of th e enzyme.