Global and site-specific M6P glycoform analysis. (A) Global analyses reveal the predominant glycan substrates for this unique PTM; The site-specific glycoforms reveal subtle differential M6P microheterogeneity among different tissues: (B, C, D) site-specific M6P glycoform annotation of the three commonly identified proteins in five mouse tissues (the number in brackets behind each glycan is the PSMs number); (E, F, G) M6P glycoform distribution (PSMs ratio) on the commonly identified glycosylation site of each protein in five mouse tissues. Glycan composition abbreviation: H = Hex/Man, N = HexNAc/GlcNAc, P = phosphate group.