Frydman J, Hartl F U
Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York 10021, USA.
Science. 1996 Jun 7;272(5267):1497-502. doi: 10.1126/science.272.5267.1497.
Molecular chaperones in the eukaryotic cytosol were shown to interact differently with chemically denatured proteins and their newly translated counterparts. During refolding from denaturant, actin partitioned freely between 70-kilodalton heat shock protein, the bulk cytosol, and the chaperonin TCP1-ring complex. In contrast, during cell-free translation, the chaperones were recruited to the elongating polypeptide and protected it from exposure to the bulk cytosol during folding. Posttranslational cycling between chaperone-bound and free states was observed with subunits of oligomeric proteins and with aberrant polypeptides; this cycling allowed the subunits to assemble and the aberrant polypeptides to be degraded. Thus, folding, oligomerization, and degradation are linked hierarchically to ensure the correct fate of newly synthesized polypeptides.
真核细胞质中的分子伴侣与化学变性蛋白及其新翻译的对应物相互作用方式不同。在从变性剂中复性的过程中，肌动蛋白可在70千道尔顿热休克蛋白、大部分细胞质和伴侣蛋白TCP1环复合物之间自由分配。相比之下，在无细胞翻译过程中，分子伴侣被招募到延伸的多肽上，并在折叠过程中保护其免受大部分细胞质的影响。寡聚蛋白亚基和异常多肽存在伴侣蛋白结合态与游离态之间的翻译后循环；这种循环使亚基得以组装，异常多肽得以降解。因此，折叠、寡聚化和降解在层次上相互关联，以确保新合成多肽的正确命运。
