Modulation of striated muscle contraction by binding of myosin binding protein C to actin

• Published in: Bioarchitecture Vol. 1; no. 6; pp. 277 - 283
• Main Authors: Luther, Pradeep K., Craig, Roger
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.11.2011
• Subjects: C-protein; cardiac muscle regulation; electron tomography; sarcomere structure; thick filament structure
• ISSN: 1949-0992; 1949-100X
• DOI: 10.4161/bioa.1.6.19341

Myosin binding protein C (MyBP-C or C-protein) is a protein of the thick (myosin-containing) filaments of striated muscle thought to be involved in the modulation of cardiac contraction in response to β-adrenergic stimulation. The mechanism of this modulation is unknown, but one possibility is through transient binding of the N-terminal end of MyBP-C to the thin (actin-containing) filaments. While such binding has been demonstrated in vitro, it was not known until recently whether such a link between thick and thin filaments also occurred in vivo. Here we review a recent paper in which electron microscopy (EM) is used to directly demonstrate MyBP-C links between myosin and actin filaments in the intact sarcomere, suggesting a possible physical mechanism for modulating filament sliding. Molecular details of MyBP-C binding to actin have recently been elucidated by EM of isolated filaments: the results suggest that MyBP-C might contribute to the modulation of contraction in part by competing with tropomyosin for binding sites on actin. New results on the structure and dynamics of the MyBP-C molecule provide additional insights into the function of this enigmatic molecule.