Journal of Cell Science, Vol 112, Issue 1 69-79, Copyright © 1999 by Company of Biologists

JOURNAL ARTICLES

Identification of the A-band localization domain of myosin binding proteins C and H (MyBP-C, MyBP-H) in skeletal muscle

R Gilbert, JA Cohen, S Pardo, A Basu and DA Fischman
Department of Cell Biology, Cornell University Medical College, New York, NY 10021, USA. fisch@mail.med.cornell.edu.

Although major constituents of the thick filaments of vertebrate striated muscles, the myosin binding proteins (MyBP-C and MyBP-H) are still of uncertain function. Distributed in the cross-bridge bearing zone of the A-bands of myofibrils, in a series of transverse 43 nm stripes, the proteins are constructed of a tandem series of small globular domains, each composed of approximately 90-100 amino acids, which have sequence similarities to either the C2-set of immunoglobulins (IgC2) and the fibronectin type III (FnIII) motifs. MyBP-C is composed of ten globular domains ( approximately 130 kDa) whereas MyBP-H is smaller ( approximately 58 kDa) and consists of a unique N-terminal segment followed by four globular domains, the order of which is identical to that of MyBP-C (FnIII-IgC2-FnIII-IgC2). To improve our understanding of this protein family we have characterized the domains in each of these two proteins which are required for targeting the proteins to their native site(s) in the sarcomere during myogenesis. Cultures of skeletal muscle myoblasts were transfected with expression plasmids encoding mutant constructs of the MyBPs bearing an N-terminal myc epitope, and their localization to the A-band examined by immunofluorescence microscopy. Based on the clarity and intensity of the myc A-band signals we concluded that constructs encoding the four C-terminal motifs of MyBP-C and MyBP-H ( approximately 360 amino acids) were all that was necessary to efficiently localize each of these peptides to the A-band. Truncation mutants lacking one of these 4 domains were less efficiently targeted to the C-zone of the sarcomere. Deletion of the last C-terminal motif of MyBP-H, its myosin binding domain, abolished all localization to the A-band. A chimeric construct, HU-3C10, in which the C-terminal motif of MyBP-H was replaced by the myosin binding domain of MyBP-C, efficiently localized to the A-band. Taken together, these observations indicate that MyBP-C and MyBP-H are localized to the A-band by the same C-terminal domain, composed of two IgC2 and two FnIII motifs. A model has been proposed for the interaction and positioning of the MyBPs in the thick filament through a ternary complex of the four C-terminal motifs with the myosin rods and titin.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				M. A. Ackermann, L.-Y. R. Hu, A. L. Bowman, R. J. Bloch, and A. Kontrogianni-Konstantopoulos Obscurin Interacts with a Novel Isoform of MyBP-C Slow at the Periphery of the Sarcomeric M-Band and Regulates Thick Filament Assembly Mol. Biol. Cell, June 15, 2009; 20(12): 2963 - 2978. [Abstract] [Full Text] [PDF]

				R. D. S. Dixon, D. K. Arneman, A. S. Rachlin, N. R. Sundaresan, M. J. Costello, S. L. Campbell, and C. A. Otey Palladin Is an Actin Cross-linking Protein That Uses Immunoglobulin-like Domains to Bind Filamentous Actin J. Biol. Chem., March 7, 2008; 283(10): 6222 - 6231. [Abstract] [Full Text] [PDF]

				E. Flashman, C. Redwood, J. Moolman-Smook, and H. Watkins Cardiac Myosin Binding Protein C: Its Role in Physiology and Disease Circ. Res., May 28, 2004; 94(10): 1279 - 1289. [Abstract] [Full Text] [PDF]

				I. A. Barash, L. Mathew, A. F. Ryan, J. Chen, and R. L. Lieber Rapid muscle-specific gene expression changes after a single bout of eccentric contractions in the mouse Am J Physiol Cell Physiol, February 1, 2004; 286(2): C355 - C364. [Abstract] [Full Text]

				R. E. Welikson and D. A. Fischman The C-terminal IgI domains of myosin-binding proteins C and H (MyBP-C and MyBP-H) are both necessary and sufficient for the intracellular crosslinking of sarcomeric myosin in transfected non-muscle cells J. Cell Sci., January 9, 2002; 115(17): 3517 - 3526. [Abstract] [Full Text] [PDF]

				J. Erdmann, J.o. Raible, J. Maki-Abadi, M. Hummel, J. Hammann, B. Wollnik, E. Frantz, E. Fleck, R. Hetzer, and V. Regitz-Zagrosek Spectrum of clinical phenotypes and gene variants in cardiac myosin-binding protein C mutation carriers with hypertrophic cardiomyopathy J. Am. Coll. Cardiol., August 1, 2001; 38(2): 322 - 330. [Abstract] [Full Text] [PDF]

				C. C. Witt, B. Gerull, M. J. Davies, T. Centner, W. A. Linke, and L. Thierfelder Hypercontractile Properties of Cardiac Muscle Fibers in a Knock-in Mouse Model of Cardiac Myosin-binding Protein-C J. Biol. Chem., February 9, 2001; 276(7): 5353 - 5359. [Abstract] [Full Text] [PDF]