BIO 320 Lecture Notes - Lecture 27: Myosin Light Chain, Hearing Loss, Vaccinia
Document Summary
Severing of older filaments by cofilin/adf, leading to disassembly at newly generated minus ends behind the leading edge. Gelsolin and capz are inhibited by pip2 near plasma membrane to minimize severing and capping there. Cofilin/adf binds f-actin, preferentially to part that contains adp- actin. It severs f-actin there to generate free minus ends that disassemble. The net result is treadmilling of the entire branched network of actin filaments. Actin assembly can propel some bacteria (e. g. , listeria and shigella) or viruses (e. g. , vaccinia) through the cell. The bacterial protein acta (instead of wasp and cdc42-gtp) binds to and activates the arp complex. Listeria monocytogenes with actin comet tails shown below! Wasp is also recruited to clathrin-coated endocytic vesicles. The movement of such vesicles away from the plasma membrane is driven by arp-mediated assembly of actin filaments. Many crosslinking proteins organize different assemblies of actin filaments; for example: Common features of myosin heavy chains: (conserved) globular head domain:
