几十年来，血清素化被认为是一种新型蛋白质翻译后修饰，其中谷氨酰胺残基和血清素通过转氨作用形成异肽键。转谷氨酰胺酶 2（也称为 TGM2 或 TGase2）被证明是该 PTM 的主要“写入”酶，并且许多关键调节蛋白（包括小 GTP 酶、纤连蛋白、纤维蛋白原、血清素转运蛋白和组蛋白 H3）已被证实。被表征为血清素化的底物。然而，由于缺乏血清素化谷氨酰胺的泛特异性抗体，血清素化的精确富集和蛋白质组分析仍然具有挑战性。在我们之前的研究中，我们开发了一种芳基重氮探针，以生物正交方式特异性标记蛋白质血清素化，这取决于 pH 控制的化学选择性快速偶氮偶联反应。在这里，我们报告了光活性芳基重氮生物素探针在癌细胞中血清素化蛋白质组的整体分析中的应用。因此，从 HCT 116 细胞中鉴定出超过 1,000 种血清素化蛋白，其中许多与癌发生高度相关。此外，由于我们化学蛋白质组学方法的成功应用，确定了这些血清素化蛋白质的许多修饰位点。总体而言，这些发现为细胞蛋白血清酰化与癌症发展之间的显着关联提供了新的见解，进一步表明靶向 TGM2 介导的单胺酰化可能作为癌症治疗的一种有前景的策略。

Serotonylation has been identified as a novel protein posttranslational modification for decades, where an isopeptide bond is formed between the glutamine residue and serotonin through transamination. Transglutaminase 2 (also known as TGM2 or TGase2) was proven to act as the main "writer" enzyme for this PTM, and a number of key regulatory proteins (including small GTPases, fibronectin, fibrinogen, serotonin transporter, and histone H3) have been characterized as the substrates of serotonylation. However, due to the lack of pan-specific antibodies for serotonylated glutamine, the precise enrichment and proteomic profiling of serotonylation still remain challenging. In our previous research, we developed an aryldiazonium probe to specifically label protein serotonylation in a bioorthogonal manner, which depended on a pH-controlled chemoselective rapid azo-coupling reaction. Here, we report the application of a photoactive aryldiazonium-biotin probe for the global profiling of serotonylation proteome in cancer cells. Thus, over 1,000 serotonylated proteins were identified from HCT 116 cells, many of which are highly related to carcinogenesis. Moreover, a number of modification sites of these serotonylated proteins were determined, attributed to the successful application of our chemical proteomic approach. Overall, these findings provided new insights into the significant association between cellular protein serotonylation and cancer development, further suggesting that to target TGM2-mediated monoaminylation may serve as a promising strategy for cancer therapeutics.