Identification of the full-length coding sequence for human galactosyltransferase (beta-N-acetylglucosaminide: beta 1,4-galactosyltransferase)

A lambda gt11 human placenta cDNA library was screened using a cDNA probe encoding the COOH-terminal region of human beta 1,4-galactosyltransferase and with a synthetic oligonucleotide having a sequence corresponding to that of the 5' end of the cDNA probe. The newly isolated cDNA was found to code for the NH2-terminal and the 5'-untranslated region, primed at an (A)8 region in the coding sequence. A complete amino acid sequence has been deduced which shows only one membrane anchoring domain near the NH2-terminus. Comparison of the sequence to the soluble enzyme suggests proteolytic cleavage at Arg 77. Presently obtained information of human beta 1,4-galactosyltransferase makes it possible to study DNA mutations responsible for genetic defects such as the altered expression of galactosyltransferase found in a variant of congenital dyserythropoietic anemia type II (HEMPAS).