Temperature sensitivity of vinblastine-induced tubulin polymerization in the presence of microtubule-associated proteins.
The antitumor drug vinblastine has been a useful probe for examining the interaction of tubulin with the microtubule-associated proteins (MAPs), specifically with tau and MAP 2. Although tau and MAP 2 can stimulate microtubule assembly in vitro, their specific interactions with tubulin are known to differ. For example, in the presence of vinblastine, both tau and MAP 2 cause tubulin to form spirals, but tau causes formation of clustered spirals of high turbidity, while MAP 2 causes formation of loose spirals of low turbidity [Ludueña et al., J. Biol. Chem. 259, 12890-12898 (1984)]. Although cold temperatures can inhibit microtubule assembly, cold has no effect on vinblastine-induced tubulin spiral formation. Consequently, we used the vinblastine-tubulin system to examine the interactions of tau and MAP 2 with tubulin at low temperatures. We found that tau-tubulin-vinblastine complexes form about as well at 0 degree C as at 37 degrees C. In contrast, MAP 2-tubulin-vinblastine complexes form much less well at 0 degrees C than at 37 degrees C. We find, however, that MAP 2, at 0 degrees C, will strongly inhibit, and even reverse, formation of the tau-tubulin-vinblastine complex. This suggests that the temperature-sensitive factor is the MAP 2-stimulated tubulin-tubulin interaction rather than the MAP 2-tubulin interaction per se; this raises the possibility that the tubulin-tubulin interactions stimulated by tau differ in their temperature sensitivity from those stimulated by MAP 2.
Prasad
V
V
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760.
Jordan
M A
MA
Ludueña
R F
RF
D000818:Animals; D002417:Cattle; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000494:pharmacology*; D008870:Microtubules / Q000737:chemistry / Q000648:ultrastructure; D011108:Polymers / Q000737:chemistry; D013696:Temperature; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D014747:Vinblastine / Q000378:metabolism / Q000494:pharmacology*; D016875:tau Proteins / Q000378:metabolism / Q000494:pharmacology
D008869:Microtubule-Associated Proteins; D011108:Polymers; D014404:Tubulin; D016875:tau Proteins; D014747:Vinblastine