C-linked glycosylation is essential for the trafficking, folding and function of secretory and transmembrane proteins involved in cellular communication processes. The tryptophan C-mannosyltransferase (CMT) enzymes that install the modification attach a mannose to the first tryptophan of WxxW/C sequons in nascent polypeptide chains by an unknown mechanism.

Reference
Pubmed: Bloch JS, John A, Mao R, Mukherjee S, Boilevin J, Irobalieva RN, Darbre T, Scott NE, Reymond JL, Kossiakoff AA, Goddard-Borger ED, Locher KP. Structure, sequon recognition and mechanism of tryptophan C-mannosyltransferase. Nat Chem Biol. 2023 May;19(5):575-584. doi: 10.1038/s41589-022-01219-9.