Most eukaryotic genes encode polypeptides that are either obligate members of hetero-stoichiometric complexes or clients of organelle-targeting pathways. Proteins in these classes can be released from the ribosome as "orphans"-newly synthesized proteins not associated with their stoichiometric binding partner(s) and/or not targeted to their destination organelle. Here we integrate recent findings suggesting that although cells selectively degrade orphan proteins under homeostatic conditions, they can preserve them in chaperone-regulated biomolecular condensates during stress. These orphan protein condensates activate the heat shock response (HSR) and represent subcellular sites where the chaperones induced by the HSR execute their functions. Reversible condensation of orphan proteins may broadly safeguard labile precursors during stress.

中文翻译：

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保存或销毁：孤儿蛋白蛋白质稳态和热休克反应。


大多数真核基因编码多肽，这些多肽要么是异化学计量复合物的专性成员，要么是细胞器靶向途径的客户端。这些类别的蛋白质可以作为“孤儿”从核糖体中释放出来 - 新合成的蛋白质，与其化学计量结合伴侣无关和/或不靶向其目的地细胞器。在这里，我们整合了最近的发现，表明尽管细胞在稳态条件下选择性地降解孤儿蛋白，但它们可以在应激期间将它们保存在伴侣调节的生物分子凝聚物中。这些孤儿蛋白凝聚物激活热休克反应 （HSR） 并代表 HSR 诱导的伴侣执行其功能的亚细胞位点。孤儿蛋白的可逆缩合可以在应激期间广泛保护不稳定的前体。