ANAT 262 Lecture Notes - Lecture 16: Spindle Pole Body, Atp Hydrolysis, Kinesin
15 Jul 2016
School
Department
Course
Professor
Document Summary
Dynamics allow the microtubule cytoskeleton to rapidly reorganize during mitosis. Mts are essential for a broad range of cell functions: Transport and organelle positioning: tracks for molecular motors. Alpha: non-exchangeable gtp site: locked in place, structural role. Multiple isoforms: 7 alpha genes and 7 beta genes, differences mainly in the c- terminal tail, which mediate interactions with accessory proteins tailored to different cell types. Longitudinal contacts: heterodimer contacts another, along proto-filament = strong interaction. Lateral contact: alpha-alpha and beta-beta contact except at the seam: alpha-beta. Microtubules can have different protofilament numbers: almost all are 13 protofilament inside cells since it is the only geometry in which protofilaments are straight => energetically favourable. Gtp binding and hydrolysis have chemically different filament ends (cc (- end) > cc (+end): ntp binding favours polymerization by increasing affinity of subunit for polymer (increase kon (ntp), dynamic instability: delay between subunits addition and gtp hydrolysis leads to a gtp cap.
