Muscle phosphorylase kinase is not a substrate of AMP-activated protein kinase.
AMP-activated protein kinase (AMPK) and cAMP-dependent protein kinase (cAMPK) have been reported to phosphorylate sites on phosphorylase kinase (PhK). Their target residues Ser 1018 and Ser 1020, respectively, are located in the so-called multi-phosphorylation domain in the PhK alpha subunit. In PhK preparations, only one of these serines is phosphorylated, but never both of them. The aim of this study was to determine whether phosphorylation by cAMPK or AMPK would influence subsequent phosphorylation by the other kinase. Surprisingly, employing four different PhK substrates, it could be demonstrated that, in contradiction to previous reports, PhK is not phosphorylated by AMPK.
Institut für Physiologische Chemie, Ruhr-Universität Bochum, Germany.
A
A
Beyer
A
A
Kitzerow
B
B
Crute
B E
BE
Kemp
L A
LA
Witters
L M
LM
Heilmeyer
D055372:AMP-Activated Protein Kinases; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000302:isolation & purification / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology*; D010764:Phosphorylase Kinase / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D013379:Substrate Specificity
D017931:DNA Primers; D009097:Multienzyme Complexes; D010764:Phosphorylase Kinase; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases