PRIMARY STRUCTURE OF HUMAN LIVER-GLYCOGEN SYNTHASE DEDUCED BY CDNA CLONING

The cDNA for human liver glycogen synthase was isolated by screening a human liver cDNA library constructed in lambda gt11. The full cDNA wa s 2912 bp in length. It coded for a protein of 703 amino acid residues with a molecular mass of 80.9 kDa. The number of amino acids was iden tical to and the deduced amino acid sequence homology was 92% that of the rat liver enzyme. The human and rat liver glycogen synthases are t runcated by 34 amino acids compared to the human muscle enzyme, and by 32 amino acids compared to the rabbit muscle enzyme. The amino acid s imilarity between human liver and human muscle glycogen synthase was o nly 69%. It was least similar in the N and C terminal regions of the m olecule. Two highly conserved regions are present in all published ami no acid sequences for glycogen synthase, including those of the two ye ast enzymes. These regions include the amino acid sequences from 201 t o 400 and 501 to 600. This high conservation suggests that the catalyt ic site and the glucose-6-P and nucleotide allosteric sites are includ ed in these regions. (C) 1994 Academic Press, Inc.