CHARACTERIZATION OF BETA-1-]4 GALACTOSYLTRANSFERASE PURIFIED FROM RAT-LIVER MICROSOMES

Beta-1 --> 4 galactosyltransferase was purified from rat liver microsomes. Catalytic properties of the enzyme resembled those of previously purified soluble and membrane-bound beta-1 --> 4 galactosyltransferases. The enzyme purified in the present study showed a major band around a molecular weight of 53,000 on SDS-PAGE. The NH2-terminal sequence of the enzyme was determined up to the 20th residue. The sequence was identical to the amino acid sequence from Ala-13 to Lys-32 deduced from mouse beta-1 --> 4 galactosyltransferase cDNA. These results suggest that most of the mature enzyme in rat liver microsomes is produced by removal of the NH2-terminal 12 amino acids from a precursor polypeptide.