title: Type II myosin regulatory light chain relieves auto-inhibition of myosin-heavy-chain function.
abstract: The F-actin based motor protein myosin II has a key role in cytokinesis. Here we show that the Schizosaccharomyces pombe regulatory light chain (RLC) protein Rlc1p binds to Myo2p in manner that is dependent on the IQ sequence motif (the RLC-binding site), and that Rlc1p is a component of the actomyosin ring. Rlc1p is important for cytokinesis at all growth temperatures and is essential for this process at lower temperatures. Interestingly, all deleterious phenotypes associated with the loss of Rlc1p function are suppressed by deletion of the RLC binding site on Myo2p. We conclude that the sole essential function of RLCs in fission yeast is to relieve the auto-inhibition of myosin II function, which is mediated by the RLC-binding site, on the myosin heavy chain (MHC).
authors.affiliation: Cell Division Laboratory, Institute of Molecular Agrobiology, The National University of Singapore, 1 Research Link, Singapore 117604.
authors.forename: N I
authors.initials: NI
authors.lastname: Naqvi
authors.forename: K C
authors.initials: KC
authors.lastname: Wong
authors.forename: X
authors.initials: X
authors.lastname: Tang
authors.forename: M K
authors.initials: MK
authors.lastname: Balasubramanian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D024722:Cardiac Myosins; D018797:Cell Cycle Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D044783:F-Box Proteins; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains / Q000502:physiology*; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins; D044767:Ubiquitin-Protein Ligases
chemical_list: D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D044783:F-Box Proteins; D018994:Myosin Light Chains; D009419:Nerve Tissue Proteins; D029702:Schizosaccharomyces pombe Proteins; C513274:cdc4 protein, S pombe; C092344:mRpL47 protein, Drosophila; C107184:myosin light chain 2; C490463:rlc1 protein, S pombe; D044767:Ubiquitin-Protein Ligases; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains