BIOL 2P03 Lecture 15: Cell bio week 8 b
10 Mar 2017
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3 steps to actin polymerization: see slideshow. Critical conc at positive end is lower than that of negative end: known as treadmilling. In vivo: many signaling components act through regulatory proteins, highly regulated process, tread milling becomes faster and more complex in living cells. Profilin: when you have profiling g- actin, this can only be added to the positive end, promotes polymerization at positive end. Cofilin: binds to adp actin molecules near negative end of f-actin, can break down, creates more negative ends that can then be further depolymerized, powerful factor in depolymerisation at negative end. Actin can also be cross-linked to plasma membrane proteins via adaptor proteins: dystrophin is the only non actin-actin linker, it links actin to plasma membrane protein. Exam q: describe process of myosin based movement. When atp binds to myosin it realeases f-actin. Step 2: atp hydrolosis changes structure, myosin reaches forward and binds to new region of actin.
