Protein ubiquitination has become one of the most extensively studied post-translational modifications. Originally discovered as a critical element in highly regulated proteolysis, ubiquitination is now regarded as essential for many other cellular processes. This results from the unique features of ubiquitin (Ub) and its ability to form various homo- and heterotypic linkage types involving one of the seven different lysine residues or the free amino group located at its N-terminus. While K48- and K63-linked chains are broadly covered in the literature, the other types of chains assembled through K6, K11, K27, K29, and K33 residues deserve equal attention in the light of the latest discoveries. Here, we provide a concise summary of recent advances in the field of these poorly understood Ub linkages and their possible roles in vivo.

中文翻译：

---

超越 K48 和 K63：非经典蛋白质泛素化

蛋白质泛素化已成为研究最广泛的翻译后修饰之一。泛素化最初被发现是高度调节的蛋白水解的关键元素，现在被认为是许多其他细胞过程必不可少的。这是由于泛素 (Ub) 的独特特征及其形成涉及七个不同赖氨酸残基之一或位于其 N 末端的游离氨基的各种同型和异型连接类型的能力。虽然 K48 和 K63 连接的链在文献中被广泛涵盖，但根据最新发现，通过 K6、K11、K27、K29 和 K33 残基组装的其他类型的链也值得同等关注。在这里，我们简要总结了这些知之甚少的 Ub 链接领域的最新进展及其在体内的可能作用。