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Mol Biol Cell. 2003 Aug;14(8):3180-91. Epub 2003 Jun 13.

A novel variant of cardiac myosin-binding protein-C that is unable to assemble into sarcomeres is expressed in the aged mouse atrium.

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1
Department of Biology, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.

Abstract

Cardiac myosin-binding protein-C (MyBP-C), also known as C-protein, is one of the major myosin-binding proteins localizing at A-bands. MyBP-C has three isoforms encoded by three distinct genes: fast-skeletal, slow-skeletal, and cardiac type. Herein, we are reporting a novel alternative spliced form of cardiac MyBP-C, MyBP-C(+), which includes an extra 30 nucleotides, encoding 10 amino acids in the carboxyl-terminal connectin/titin binding region. This alternative spliced form of MyBP-C(+) has a markedly decreased binding affinity to myosin filaments and connectin/titin in vitro and does not localize to A-bands in cardiac myocytes. When MyBP-C(+) was expressed in chicken cardiac myocytes, sarcomere structure was markedly disorganized, suggesting it has possible dominant negative effects on sarcomere organization. Expression of MyBP-C(+) is hardly detected in ventricles through cardiac development, but its expression gradually increases in atria and becomes the dominant form after 6 mo of age. The present study demonstrates an age-induced new isoform of cardiac MyBP-C harboring possible dominant negative effects on sarcomere assembly.

PMID:
12925755
PMCID:
PMC181559
DOI:
10.1091/mbc.E02-10-0685
[Indexed for MEDLINE]
Free PMC Article
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