The alpha1 and alpha2 isoforms of the AMP-activated protein kinase have similar activities in rat liver but exhibit differences in substrate specificity in vitro.
The AMP-activated protein kinase (AMPK) is a heterotrimeric complex composed of a catalytic subunit (alpha) and two regulatory subunits (beta and gamma). Two isoforms of the catalytic subunit (alpha1 and alpha2) have been identified. We show here that the alpha1- and alpha2-containing complexes contribute approximately equally to total AMPK activity in rat liver. Furthermore, expression of alpha1 or alpha2 with beta and gamma in mammalian cells demonstrates that both complexes have equal specific activity measured with the SAMS peptide. Using variant peptides, however, we show that alpha1 and alpha2 exhibit slightly different substrate preferences, which suggest that the two isoforms could play different physiological roles within the cell.
Woods
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A
MRC Molecular Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Salt
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Scott
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Hardie
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DG
Carling
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D
D055372:AMP-Activated Protein Kinases; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D051381:Rats; D013379:Substrate Specificity; D014162:Transfection
D018076:DNA, Complementary; D007527:Isoenzymes; D009097:Multienzyme Complexes; D009842:Oligopeptides; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases