Diabetes, Vol 44, Issue 9 1099-1105, Copyright © 1995 by American Diabetes Association
Isolation and characterization of the human muscle glycogen synthase gene
M Orho, P Nikula-Ijas, C Schalin-Jantti, MA Permutt and LC Groop
Department of Biochemistry, University of Helsinki, Finland.
Impaired glycogen synthase (GS) activity in skeletal muscle has been
considered to be an inherited trait in patients with non-insulin-dependent
diabetes mellitus (NIDDM). We therefore isolated the human muscle GS gene
from genomic libraries and determined the genomic structure. The entire
coding region, the 5'-flanking region, and the exon-intron boundaries were
sequenced. The gene consists of 16 exons spanning approximately 27 kb of
DNA and exists as a single copy in the human genome. The negatively charged
parts with all known phosphorylation sites were coded by the first and the
last exon. A single transcription initiation site was located 167
nucleotides upstream of the initiation codon. All of the exons and the
putative promoter region were analyzed by single-strand conformation
polymorphism in 30 insulin-resistant Finnish NIDDM patients, and three
polymorphic sites were found. A missense mutation Gly464/Ser in exon 11 was
found in 2 of 228 NIDDM patients screened but in 0 of 154 control subjects.
These two patients were characterized further by severe insulin resistance
and premature arteriosclerosis. The characterization of the genomic
structure of the human muscle GS gene will facilitate studies of its role
in the development of insulin resistance and NIDDM.