Regulation of Dictyostelium myosin I and II.
Dictyostelium expresses 12 different myosins, including seven single-headed myosins I and one conventional two-headed myosin II. In this review we focus on the signaling pathways that regulate Dictyostelium myosin I and myosin II. Activation of myosin I is catalyzed by a Cdc42/Rac-stimulated myosin I heavy chain kinase that is a member of the p21-activated kinase (PAK) family. Evidence that myosin I is linked to the Arp2/3 complex suggests that pathways that regulate myosin I may also influence actin filament assembly. Myosin II activity is stimulated by a cGMP-activated myosin light chain kinase and inhibited by myosin heavy chain kinases (MHCKs) that block bipolar filament assembly. Known MHCKs include MHCK A and MHCK B, which have a novel type of kinase catalytic domain joined to a WD repeat domain, and MHC-protein kinase C (PKC), which contains both diacylglycerol kinase and PKC-related protein kinase catalytic domains. A Dictyostelium PAK (PAKa) acts indirectly to promote myosin II filament formation, suggesting that the MHCKs may be indirectly regulated by Rac GTPases.
de la Roche
M A
MA
Department of Biochemistry, Queen's University, K7L 3N6, Kingston, Ont., Canada.
Côté
G P
GP
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D015800:Protozoan Proteins; D015398:Signal Transduction; D018909:src Homology Domains
D000199:Actins; D020033:Protein Isoforms; D015800:Protozoan Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C033142:myosin-heavy-chain kinase; D009218:Myosins