Mammalian AMP-activated protein kinase is homologous to yeast and plant protein kinases involved in the regulation of carbon metabolism.

In mammals, an AMP-activated protein kinase (AMPK) phosphorylates both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase in vitro and has been proposed to play a major role in the regulation of lipid metabolism in vivo. We report here the primary sequence of rat AMPK and show that antibodies raised against synthetic peptides based on the deduced sequence of AMPK immunoprecipitate AMPK activity from rat liver extracts. AMPK has a remarkable degree of sequence identity to the proteins encoded by the yeast SNF1 gene and the plant RKIN1 gene. SNF1 protein kinase activity is essential for release of genes from glucose repression in Saccharomyces cerevisiae. Expression of cRKIN1 in yeast snf1 mutants restores SNF1 function. These results indicate that AMPK, SNF1, and RKIN1 form part of a family of protein kinases that have been highly conserved throughout evolution. Our results suggest that AMPK may be involved in the regulation of a wide range of metabolic pathways.