title: ATP-dependent formation and motility of aster-like structures with isolated calf brain microtubule proteins.
abstract: Microtubule proteins isolated from calf brain will undergo gelation-contraction in the presence of ATP. We have now examined this process by video-enhanced contrast microscopy. After ATP addition to steady-state microtubules, slow (1-5 micron/min), linear movements of particles and microtubules toward aggregation centers occur. The resulting structures resemble mitotic spindle asters. During the time when gel contraction occurs, asters move (at 1-5 micron/min) toward other nearby asters. This is accompanied by the apparent shortening of the microtubules running between the asters. This is the first example of isolated microtubules undergoing a process that has similarities to half-spindle shortening during anaphase A. Formation of aster-like structures without preformed microtubule organizing centers raises the possibility that a similar process may contribute to microtubule organization in vivo.
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D008858:Microscopy, Phase-Contrast; D008868:Microtubule Proteins / Q000378:metabolism*; D008870:Microtubules / Q000648:ultrastructure*; D009068:Movement
chemical_list: D008868:Microtubule Proteins; D000255:Adenosine Triphosphate