BSC 300 Lecture Notes - Lecture 18: Sliding Filament Theory, Myosin, Skeletal Muscle
21 Oct 2016
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Document Summary
Actin based microfilaments coordinate most animal cell motility, aspects of intercellular transport, muscle contraction and cell division. This dynamic cytoskeletal element is a polymer of the actin monomers, arranged in a consistent, polar fashion into long two-stranded helical rope like structures. Polymerization is atp dependent and the monomers are atpases (recall -tubulin is a. The filamentous structure gives the polymers the name f-actin. And the polarity provides a means for directed motor protein movement. Actin assembly/ disassembly dynamics depends on atp-actin monomers concentration. Both ends can polymerize monomers, however the barbed plus end has higher affinity for monomers and incorporates them about 10x as fast as the pointed minus end. As atp actin monomer concentration drops the plus end adds monomers faster than the minus end. At very low actin atp concentrations the minus end loses monomers faster than it adds.
