ISOLATION AND CHARACTERIZATION OF THE HUMAN MUSCLE GLYCOGEN-SYNTHASE GENE

Impaired glycogen synthase CGS) activity in skeletal muscle has been c onsidered to be an inherited trait in patients with non-insulin-depend ent diabetes mellitus (NIDDM). We therefore isolated the human muscle GS gene from genomic libraries and determined the genomic structure. T he entire coding region, the 5'-flanking region, and the exon-intron b oundaries were sequenced. The gene consists of 16 exons spanning simil ar to 27 kb of DNA and exists as a single copy in the human genome. Th e negatively charged parts with all known phosphorylation sites were c oded by the first and the last exon. A single transcription initiation site was located 167 nucleotides upstream of the initiation codon. Al l of the exons and the putative promoter region were analyzed by singl e-strand conformation polymorphism in 30 insulin-resistant Finnish NID DM patients, and three polymorphic sites were found. A missense mutati on Gly(464)/Ser in exon 11 was found in 2 of 228 NIDDM patients screen ed but in 0 of 154 control subjects. These two patients were character ized further by severe insulin resistance and premature arterioscleros is. The characterization of the genomic structure of the human muscle GS gene will facilitate studies of its role in the development of insu lin resistance and NIDDM.