Primary Citation of Related Structures: 3JTD, 3JVT
PubMed Abstract:
In regulated myosin, motor and enzymatic activities are toggled between the on-state and off-state by a switch located on its lever arm domain, here called the regulatory domain (RD). This region consists of a long alpha-helical "heavy chain" stabilized by a "regulatory" light chain (RLC) and an "essential" light chain (ELC) ...
In regulated myosin, motor and enzymatic activities are toggled between the on-state and off-state by a switch located on its lever arm domain, here called the regulatory domain (RD). This region consists of a long alpha-helical "heavy chain" stabilized by a "regulatory" light chain (RLC) and an "essential" light chain (ELC). The on-state is activated by phosphorylation of the RLC of vertebrate smooth muscle RD or by direct binding of Ca(2+) to the ELC of molluscan RD. Crystal structures are available only for the molluscan RD. To understand in more detail the pathway between the on-state and the off-state, we have now also determined the crystal structure of a molluscan (scallop) RD in the absence of Ca(2+). Our results indicate that loss of Ca(2+) abolishes most of the interactions between the light chains and may increase the flexibility of the RD heavy chain. We propose that disruption of critical links with the C-lobe of the RLC is the key event initiating the off-state in both smooth muscle myosins and molluscan myosins.
Related Citations:
Structure of the Regulatory Domain of Scallop Myosin at 2 A Resolution: Implications for Regulation. Houdusse, A., Cohen, C. (1996) Structure 4: 21
Structure of the Regulatory Domain of Scallop Myosin at 2.8 A Resolution. Xie, X., Harrison, D.H., Schlichting, I., Sweet, R.M., Kalabokis, V.N., Szent-Gyorgyi, A., Cohen, C. (1994) Nature 368: 306
Organizational Affiliation:
Rosenstiel Basic Medical Sciences Research Center, Biology Department, Brandeis University, Waltham, MA 02453-2728, USA. himmel@cabm.rutgers.edu
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