Regulation of the microtubule steady state in vitro by ATP

摘要: Abstract ATP increases microtubule steady state assembly and disassembly rates in vitro a concentration-dependent manner. Bovine brain microtubules, composed of 75% tubulin 25% high molecular weight microtubule-associated proteins (MAPs), were purified by three cycles the absence ATP. When assembled to state, these microtubules add dimers at one end lose them other unidirectional assembly-disassembly process. In presence 1.0 mM flow from as much 20 fold, revealed loss 3H-GTP uniformly labeled under GTP chase conditions rate following addition 50 μM podophyllotoxin. UTP, CTP 5′ adenylylimidodiphosphate (AMP-PNP) cannot substitute for producing this effect. Furthermore, increase persists after is removed. Thus centrifuged through sucrose cushions separate nucleotides continue exhibit increased next cycle It possible that an ATP-dependent protein kinase responsible observed rate. A activity associated with MAPs has been reported be cAMP-dependent (Sloboda et al., 1975). We have found adenylate cyclase microtubules. Whether contaminant or due specific protein, whether its functionally linked ATP, remain determined.