1wdc
From Proteopedia
SCALLOP MYOSIN REGULATORY DOMAIN
Structural highlights
Function[MYS_ARGIR] Muscle contraction. Myosin is a protein that binds to F-actin and has ATPase activity that is activated by F-actin. [MLE_ARGIR] In molluscan muscle, calcium regulation is associated with myosin rather than with actin. Muscle myosin contains two types of light chains: the catalytic light chain, essential for ATPase activity, and the regulatory light chain, a calcium-binding protein responsible for Ca(2+) dependent binding and Ca(2+) dependent Mg-ATPase activity. [MLR_ARGIR] In molluscan muscle, calcium regulation is associated with myosin rather than with actin. Muscle myosin contains two types of light chains: the catalytic light chain, essential for ATPase activity, and the regulatory light chain, a calcium-binding protein responsible for Ca(2+) dependent binding and Ca(2+) dependent Mg-ATPase activity. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: In contrast to the myosins of vertebrate skeletal muscle, molluscan myosins are regulated molecules whose enzymatic activity is switched on by the direct binding of Ca2+. The head portion (S1) of the molecule consists of a motor domain and a regulatory domain (RD) containing a 'regulatory' and an 'essential' light chain (RLC and ELC, respectively). The structures of scallop myosin RD with bound Ca2+, as well as the S1 fragment of chicken skeletal muscle myosin, have been determined previously to 2.8 A resolution. RESULTS: We have determined the structure at 2.0 A resolution of scallop myosin RD with bound Ca2+. The unusual coordination at the specific Ca(2+)-binding site in the ELC has now been clarified, as has the structural basis for Mg2+ binding to the RLC. A comparison of the scallop RD structure with that in the chicken S1 structure shows differences in the bending of the two RDs in two different places. CONCLUSIONS: Based on these structural results, a model for regulation is proposed in which the Ca(2+)-bound RD is a rigid structure, and transient flexibility of the Ca(2+)-free RD allows the myosin heads to make stabilizing intramolecular linkage which shut off the motor. Structure of the regulatory domain of scallop myosin at 2 A resolution: implications for regulation.,Houdusse A, Cohen C Structure. 1996 Jan 15;4(1):21-32. PMID:8805510[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||
