Abstract
Myosin II and V are important for the generation and segregation of subcellular compartments. We observed that vesicular myosin II and V were associated with the protein scaffolding of a common subset of vesicles by density sedimentation, electron microscopy, and immunofluorescence. Solubilization of either myosin II or V was caused by polyphosphates with the following efficacy at 10 mM: for myosin II ATP-Mg2+ = ATP = AMP-PNP (5'- adenylyl imidodiphosphate) > pyrophosphate = tripolyphosphate >> tetrapolyphosphate = ADP > cAMP = Mg2+; and for myosin V pyrophosphate = tripolyphosphate > ATP-Mg2+ = ATP = AMP-PNP >> ADP = tetrapolyphosphate > cAMP = Mg2+. Consequently, we suggest solubilization was not an effect of phosphorylation, hydrolysis, or disassociation of myosin from actin filaments. Scatchard analysis of myosin V binding to stripped dense vesicles showed saturable binding with a K(m) of 10 nM. Analysis of native vesicles indicates that these sites are fully occupied. Together, these data show there are over 100 myosin Vs/vesicle (100-nm radius). We propose that polyphosphate anions bind to myosin II and V and induce a conformational change that disrupts binding to a receptor.
Original language | English (US) |
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Pages (from-to) | 2598-2606 |
Number of pages | 9 |
Journal | Journal of Biological Chemistry |
Volume | 275 |
Issue number | 4 |
DOIs | |
State | Published - Jan 28 2000 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology