Structural highlights
Function
[KAR3_YEAST] Essential for yeast nuclear fusion during mating. KAR3 is a bifunctional protein having a kinesin-like motor domain joined to a distinct microtubule binding domain. It may mediate microtubule sliding during nuclear fusion and possibly mitosis. May interact with spindle microtubules to produce an inwardly directed force acting upon the poles. KAR3 function antagonizes CIP8 and KIP1 outward force action. KAR3 motor activity is directed toward the microtubule's minus end.[1] [2]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Molecular motors move along actin or microtubules by rapidly hydrolyzing ATP and undergoing changes in filament-binding affinity with steps of the nucleotide hydrolysis cycle. It is generally accepted that motor binding to its filament greatly increases the rate of ATP hydrolysis, but the structural changes in the motor associated with ATPase activation are not known. To identify the conformational changes underlying motor movement on its filament, we solved the crystal structures of three kinesin mutants that decouple nucleotide and microtubule binding by the motor, and block microtubule-activated, but not basal, ATPase activity. Conformational changes in the structures include a disordered loop and helices in the switch I region and a visible switch II loop, which is disordered in wild-type structures. Switch I moved closer to the bound nucleotide in two mutant structures, perturbing water-mediated interactions with the Mg2+. This could weaken Mg2+ binding and accelerate ADP release to activate the motor ATPASE: The structural changes we observe define a signaling pathway within the motor for ATPase activation that is likely to be essential for motor movement on microtubules.
A structural pathway for activation of the kinesin motor ATPase.,Yun M, Zhang X, Park CG, Park HW, Endow SA EMBO J. 2001 Jun 1;20(11):2611-8. PMID:11387196[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Meluh PB, Rose MD. KAR3, a kinesin-related gene required for yeast nuclear fusion. Cell. 1990 Mar 23;60(6):1029-41. PMID:2138512
- ↑ Shanks RM, Kamieniecki RJ, Dawson DS. The Kar3-interacting protein Cik1p plays a critical role in passage through meiosis I in Saccharomyces cerevisiae. Genetics. 2001 Nov;159(3):939-51. PMID:11729143
- ↑ Yun M, Zhang X, Park CG, Park HW, Endow SA. A structural pathway for activation of the kinesin motor ATPase. EMBO J. 2001 Jun 1;20(11):2611-8. PMID:11387196 doi:http://dx.doi.org/10.1093/emboj/20.11.2611
