“…A complementary method to AP-MS and PL for analyzing PPIs involves covalent cross-linking (Liu et al, 2015;Wang, 2017;Nguyen et al, 2018;Yu and Huang, 2018). Genetic code expansion by amber codon suppression has enabled sitespecific incorporation of non-canonical amino acids (ncAAs) into proteins (Wang et al, 2001;Wang and Schultz, 2004;Wang et al, 2006;de la Torre and Chin, 2021;Shandell et al, 2021). Many ncAAs, including photo-activated ncAAs (Chin et al, 2002a;Chin et al, 2002b;Zhang et al, 2011;Lin et al, 2014;Yang et al, 2016) and those with fine-tuned bio-reactivity to capture protein binders (Xiang et al, 2013;Chen X.-H. et al, 2014;Furman et al, 2014;Xiang et al, 2014;Xuan et al, 2016;Cigler et al, 2017;Wang, 2017;Nguyen et al, 2018;Shang et al, 2018;Wang et al, 2018;Yang et al, 2019;Liu et al, 2020;Liu J. et al, 2021), has been successfully incorporated into proteins.…”