Identifying the Heterotrimeric Complex Stoichiometry of AMPK in Skeletal Muscle by Immunoprecipitation.

The 5'-AMP-activated protein kinase is a complicated enzyme consisting of three different subunits, each of which is expressed as two or three isoforms. This gives the possibility of 12 different heterotrimeric complexes, which could have diverse functions within the cell. To map out which of these complexes are present and to what extent in skeletal muscle, we have used the immunoprecipitation technique and analyzed both the precipitates and the remaining supernatants for coprecipitation of complex partners. We have fine-tuned this method to give the best results on lysates from the skeletal muscle, liver, and heart muscle from mouse to man.