Sequence of the human glycogen-associated regulatory subunit of type 1 protein phosphatase and analysis of its coding region and mRNA level in muscle from patients with NIDDM.
Impaired insulin-stimulated glycogen synthesis of peripheral tissues is a characteristic feature of many patients with non-insulin-dependent diabetes mellitus (NIDDM) and their first-degree relatives with normal glucose tolerance, suggesting putative inherited defects in this metabolic pathway. In previous studies, we have failed to reveal mutations in the coding regions of the muscle-specific glycogen synthase gene and the three genes that encode the catalytic subunits of protein phosphatase 1 (PP1) as frequent causes of insulin resistance. Because the glycogen-associated regulatory subunit of protein phosphatase 1 (PP1 G-subunit) plays a key role in the insulin stimulation of glycogen synthesis and the activity of PP1 is decreased in insulin-resistant subjects, we have now cloned the human G-subunit cDNA to search for abnormalities in the corresponding gene (designated PPP1R3 in the human genome nomenclature) in patients with NIDDM. The human cDNA was isolated from a skeletal muscle cDNA library and was found to encode a 126-kDa protein, which shows 73% amino acid identity to the rabbit PP1 G-subunit. The human G-subunit cDNA from 30 insulin-resistant NIDDM patients was analyzed for genetic variations in the G-subunit by using single-stranded conformation polymorphism (SSCP) scanning of reversely transcribed mRNA. One variant SSCP profile was detected in the region encoding the COOH-terminal part of the PP1 G-subunit in only one NIDDM patient, and subsequent nucleotide sequencing showed a C to A transversion on one allele at base position 2792. This change predicts an amino acid substitution from alanine to glutamic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
Chen
Y H
YH
Department of Biochemistry, The University, Dundee, Scotland, U.K.
Hansen
L
L
Chen
M X
MX
Bjørbaek
C
C
Vestergaard
H
H
Hansen
T
T
Cohen
P T
PT
Pedersen
O
O
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology* / Q000235:genetics; D005260:Female; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D054645:Protein Phosphatase 1; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D012016:Reference Values; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D046911:Macromolecular Substances; D012333:RNA, Messenger; D006003:Glycogen; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D005947:Glucose