BIOL 200 Lecture Notes - Lecture 30: Microtubule, Atp Hydrolysis, Mitosis
Document Summary
Formation of the gtp cap: when mt assembly happens faster than the rate of gtp hydrolysis. Tubulin molecules with bound gtp add to end of mt: happens in conditions with a high enough [free tubulin] Dynamic instability: loss of cap leads to rapid shrinking. If polymerization slows down, the gtp hydrolysis catches up and is now converted to. Protofilaments containing gdp tubulin peel away from the mt wall. Gdp tubulin is released to the cytosol. Result = rapid shrinking: note: tubulin-gdp has a lower affinity for the tubulin polymer or mt. Gtp hydrolysis changes subunit conformation, forcing the protofilament into a curved shape. Destabilization of mt through gtp hydrolysis results in instability in mt structure. Roles of mt inside the cell: organelle positioning, vesicle trafficking, mitotic spindle pulling apart chromosomes. Cells control & promote mt assembly by adding nucleating sites known as microtubule. Special kind of tubulin used (= -tubulin) to form ring complex.
