Netzer W J, Hartl F U
Cornell Graduate School of Medical Sciences, New York, NY 10021, USA.
Trends Biochem Sci. 1998 Feb;23(2):68-73. doi: 10.1016/s0968-0004(97)01171-7.
Recent findings suggest that a combination of chaperonin-assisted and unassisted mechanisms operate in protein folding in the cytosol. While nascent chain-binding chaperones, such as Hsp70, could have a general role in maintaining the folding competence of translating polypeptide chains, the contribution of the cylindrical chaperonin complexes to overall folding is limited to a subset of aggregation-sensitive polypeptides. The majority of bacterial proteins are relatively small and they are synthesized rapidly and folded independently of the chaperonin GroEL in a posttranslational manner. Eukaryotes have a proportionally larger number of multi-domain proteins than bacteria. The individual domains of these proteins can be folded cotranslationally and sequentially. The use of this mechanism explains how large proteins fold independently of a chaperonin and could have been crucial in the evolution of a wide array of modular polypeptides in eukaryotes.
最近的研究结果表明，伴侣蛋白辅助和非辅助机制共同作用于胞质溶胶中的蛋白质折叠过程。虽然新生链结合伴侣蛋白，如热休克蛋白70（Hsp70），可能在维持正在翻译的多肽链的折叠能力方面发挥普遍作用，但圆柱形伴侣蛋白复合物对整体折叠的贡献仅限于对聚集敏感的多肽亚群。大多数细菌蛋白相对较小，它们合成迅速，并且在翻译后以独立于伴侣蛋白GroEL的方式折叠。与细菌相比，真核生物中多结构域蛋白的比例更大。这些蛋白的各个结构域可以在共翻译过程中依次折叠。这种机制的应用解释了大蛋白如何独立于伴侣蛋白进行折叠，并且在真核生物中广泛的模块化多肽的进化过程中可能至关重要。
