Grantham Julie, Ruddock Lloyd W, Roobol Anne, Carden Martin J
Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
Cell Stress Chaperones. 2002 Jul;7(3):235-42. doi: 10.1379/1466-1268(2002)007<0235:ecctcp>2.0.co;2.
We have previously observed that subunits of the chaperonin required for actin production (type-II chaperonin containing T-complex polypeptide 1 [CCT]) localize at sites of microfilament assembly. In this article we extend this observation by showing that substantially substoichiometric CCT reduces the initial rate of pyrene-labeled actin polymerization in vitro where eubacterial chaperonin GroEL had no such effect. CCT subunits bound selectively to F-actin in cosedimentation assays, and CCT reduced elongation rates from both purified actin filament "seeds" and the short and stabilized, minus-end blocked filaments in erythrocyte membrane cytoskeletons. These observations suggest CCT might remain involved in biogenesis of the actin cytoskeleton, by acting at filament (+) ends, beyond its already well-established role in producing new actin monomers.
我们之前观察到，肌动蛋白产生所需的伴侣蛋白亚基（包含T复合多肽1的II型伴侣蛋白 [CCT]）定位于微丝组装位点。在本文中，我们扩展了这一观察结果，表明亚化学计量的CCT在体外显著降低了芘标记的肌动蛋白聚合的初始速率，而真细菌伴侣蛋白GroEL没有这种作用。在共沉降试验中，CCT亚基选择性地与F-肌动蛋白结合，并且CCT降低了来自纯化的肌动蛋白丝“种子”以及红细胞膜细胞骨架中短而稳定的、负端封闭的丝的延伸速率。这些观察结果表明，CCT可能通过在丝的（+）端起作用，在肌动蛋白细胞骨架的生物发生中持续发挥作用，这超出了其在产生新的肌动蛋白单体方面已确立的作用。
