期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 104, 期 24, 页码 9994-9999出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0701181104
关键词
kinetics; load dependence; myosin; actomyosin; cytoskeleton
资金
- FIC NIH HHS [R01 TW007241, D43 TW 006230, 1R01 TW 007241-01, R01 TW006230] Funding Source: Medline
- Wellcome Trust Funding Source: Medline
Loads on molecular motors regulate and coordinate their function. In a study that directly measures properties of internally strained myosin 2 heads bound to actin, we find that human nonmuscle myosins 2A and 2B show marked load-dependent changes in kinetics of ADP release but not in nucleotide binding. We show that the ADP release rate constant is increased 4-fold by the assisting load on one head and decreased 5-fold (for 2A) or 12-fold (for 213) by the resisting load on the other. Thus these myosins, especially 2B, have marked mechanosensitivity of product release. By regulating the actin attachment of myosin heads, this provides a basis for energy-efficient tension maintenance without obstructing cellular contractility driven by other motors such as smooth muscle myosin. Whereas forward load accelerates the cycle of interaction with actin, resistive load increases duty ratio to favor tension maintenance by two-headed attachment.
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