期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 103, 期 9, 页码 3118-3123出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0505685103
关键词
cell motility; unconventional myosin; lipid signaling
资金
- NIGMS NIH HHS [R01 GM057247, GM57247] Funding Source: Medline
Myosin-I is the single-headed member of the myosin superfamily that associates with acidic phospholipids through its basic tail domain. Membrane association is essential for proper myosin-I localization and function. However, little is known about the physiological relevance of the direct association of myosin-I with phospholipids or about phospholipid headgroup-binding specificity. To better understand the mechanism of myosin-l-membrane association, we measured effective dissociation constants for the binding of a recombinant myo1c tail construct (which includes three IQ domains and bound calmodulins) to large unilamellar vesicles (LUVs) composed of phosphatidylcholine and various concentrations of phosphatidylserine (PS) or phosphatidylinositol 4,5-bisphosphate (PIP2). We found that the myo1c-tail binds tightly to LUVs containing > 60% PS but very weakly to LUVs containing physiological PS concentrations (< 40%). The myo1c tail and not the IQ motifs bind tightly to LUVs containing 2% PIP2. Additionally, we found that the myo1c tail binds to soluble inositol-1,4,5-trisphosphate with nearly the same affinity as to PIP2 in LUVs, suggesting that myolc binds specifically to the headgroup of PIP2. We also show that a GFP-myosin-1-tail chimera expressed in epithelial cells is transiently localized to regions known to be enriched in PIP2. Our results suggest that myolc does not bind to physiological concentrations of PS but rather binds tightly to PIP2.
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