Biology 2382B Lecture Notes - Lecture 13: Ras Superfamily, Leading Edge, Sarcolemma
Document Summary
Actin filaments microfilaments cortical function: responsive to extracellular signals involved in cell shape (cytoskeleton) and movement, not the same as flagellar movement note actin is first to be reorganized during mitosis. Actin based structures actin takes on many different structures based on the type of function or the type of cell unlike microtubules, actin can form networks and bundles: complex branching and mesh-works. Actin structure vertebrates have multiple actin isoforms: 4 a (muscle) b and g (not important) G-actin (globular) polymerizes into f-actin (filamentous) microfilaments: g-actin is the monomer form. Polar: f-actin is the actin polymer. Maintains polarity (+ and end) note: g-actin must be bound to atp to polymerize. When other proteins bind to actin, they bind in specific orientation due to polarity of actin. Actin assembly if nucleating center is already present, elongation faster: without nucleating site, g-actin forms its nucleus first (nucleation) G-actin polymerizes in atp form: then atp is hydrolyzed to adp.