Dual Ser and Thr phosphorylation of CPI-17, an inhibitor of myosin phosphatase, by MYPT-associated kinase.
Phosphorylation of CPI-17 and PHI-1 by the MYPT1-associated kinase (M110 kinase) was investigated. M110 kinase is a recently identified serine/threonine kinase with a catalytic domain that is homologous to that of ZIP kinase (ZIPK. GST-rN-ZIPK, a constitutively active GST fusion fragment, phosphorylates CPI-17 (but not PHI-1) to a stoichiometry of 1.7 mol/mol. Phosphoamino acid analysis revealed phosphorylation of both Ser and Thr residues. Phosphorylation sites in CPI-17 were identified as Thr 38 and Ser 12 using Edman sequencing with (32)P release and a point mutant of Thr 38.
MacDonald
J A
JA
Department of Pharmacology, Duke University Medical Center, PO Box 3813, Durham, NC 27710, USA.
Eto
M
M
Borman
M A
MA
Brautigan
D L
DL
Haystead
T A
TA
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D064550:Death-Associated Protein Kinases; D066298:In Vitro Techniques; D009124:Muscle Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D013912:Threonine; D012694:Serine; C424286:M110 kinase; D064550:Death-Associated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D043263:Myosin-Light-Chain Phosphatase