The O-GlcNActransferase (OGT) is localized to the nucleus and cytoplasm where it regulates nucleocytoplasmic proteins by modifying serine and threonine residues with a non-extended monosaccharide, b-N-Acetyl-Glucosamine (O-GlcNAc). With thousands ofknown O-GlcNAcmodifiedproteinsbut only oneOGTencoded in the mammalian genome, a prevailing question is howOGTselects its substrates. Prior work has indicated that theN-terminaltetratricopeptide repeat (TPR) domain of OGT, rather than itsC-terminalcatalytic domain, is responsible forsubcellular targeting andsubstrate selection.An additional impetus for exploring the OGT TPR domain interactome is the fact that missense mutations inOGTassociated with X-linked intellectual disability (XLID) are primarily localized to the TPR domain without substantial impact on activity or stability of the enzyme.Therefore, we adapted theBioIDlabeling method to identify interactors of a TPR-BirA* fusion protein in HeLa cells. We identified 115high confidenceinteractors representing both known and novel O-GlcNAcmodified proteins and OGT interactors. The TPR interactors are highly enriched in processes in which OGT has a known role (e.g. chromatin remodeling, cellular survival of heat stress, circadian rhythm), as well as processesin which OGT has yet to be implicated (e.g. pre-mRNA processing). Importantly,the identified TPR interactors are involved in several disease states but most notably are highly enriched in pathologies featuring intellectual disability.Theseproteinsrepresent candidateinteractors that may underlie the mechanismby which mutations in OGT lead to XLID. Furthermore, the identified interactors provide additional evidence of the importance of the TPR domain for OGT targeting and/or substrate selection.Thus, this defined interactome for the TPR domain of OGT serves as ajumping off point for future researchexploringthe role of OGT, the TPR domain, and its protein interactorsin multiple cellular processes and disease mechanisms, including intellectual disability.

中文翻译：

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O-GlcNAc转移酶的四肽重复域的无偏态的交互作用的产生表明该酶在智障中的作用。

O-GlcNAc转移酶（OGT）定位于细胞核和细胞质，在其中通过使用未扩展的单糖bN-乙酰基-葡萄糖胺（O-GlcNAc）修饰丝氨酸和苏氨酸残基来调节胞质蛋白。拥有数千种已知的O-GlcNAc修饰蛋白，而哺乳动物基因组中只有一个OGT编码，一个主要的问题是OGT如何选择其底物。先前的研究表明，OGT的N末端四肽重复序列（TPR）结构域而非其C末端催化结构域负责亚细胞靶向和底物选择。探索OGT TPR结构域相互作用基因组的另一个推动力是，OGT中的错义突变与X-相关。连锁智力障碍（XLID）主要位于TPR结构域，而对酶的活性或稳定性没有实质性影响。我们采用了BioIDlabeling方法来鉴定HeLa细胞中TPR-BirA *融合蛋白的相互作用因子。我们确定了115个高可信度的相互作用者，代表已知和新颖的O-GlcNAc修饰的蛋白质和OGT相互作用者。TPR相互作用物高度丰富于其中OGT具有已知作用的过程（例如染色质重塑，热应激的细胞存活，昼夜节律）以及尚未涉及OGT的过程（例如，mRNA前加工）。重要的是，已确定的TPR相互作用因子涉及多种疾病状态，但最显着的是丰富了具有智力障碍的病理学。这些蛋白代表候选相互作用因子，可能是OGT突变导致XLID的机制的基础。此外，