PMID:9201999

Citation	Kolman, MF and Egelhoff, TT (1997) Dictyostelium myosin heavy chain kinase A subdomains. Coiled-coil and wd repeat roles in oligomerization and substrate targeting. J. Biol. Chem. 272:16904-10
Abstract	Myosin heavy chain kinase A (MHCK A) participates in the regulation of cytoskeletal myosin assembly in Dictyostelium, driving filament disassembly via phosphorylation of sites in the myosin tail. MHCK A contains an amino-terminal coiled-coil domain, a novel central catalytic domain, and a carboxyl-terminal domain containing a 7-fold WD repeat motif. We have overexpressed MHCK A truncation constructs to clarify the roles of each of these domains. Recombinant full-length MHCK A, MHCK A lacking the predicted coiled-coil domain, and MHCK A lacking the WD repeat domain were expressed at high levels in Dictyostelium cells lacking endogenous MHCK A. Biochemical analysis of the purified proteins demonstrates that the putative coiled-coil domain is responsible for the oligomerization of the MHCK A holoenzyme. Removal of the WD repeat domain had no effect on catalytic activity toward a synthetic peptide, but did result in a 95% loss of protein kinase activity when native myosin filaments were used as the substrate. Cellular analysis confirms that the same severe loss of activity against myosin occurs in vivo when the WD repeat domain is eliminated. These results suggest that the WD repeat domain of MHCK A serves to target this enzyme to its physiological substrate.
Links	PubMed
Keywords	Animals; Calcium-Calmodulin-Dependent Protein Kinases/chemistry; Cell Division; Dictyostelium; Kinetics; Molecular Weight; Myosins/metabolism; Phosphorylation; Polymers/metabolism; Protein Conformation; Protozoan Proteins; Shadowing (Histology); Substrate Specificity
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status

References

See Help:References for how to manage references in GONUTS.