Dpy19 proteins are C-mannosyltransferases that mediate C-mannosylation of tryptophan residues on target proteins. C-mannosylation is the attachment of alpha-mannose to the indole C2 carbon of the first tryptophan residue in the consensus amino acid sequence Trp-Xaa-Xaa-Trp/Cys through a C-C bond. This reaction takes place in the endoplasmic reticulum (ER) lumen. Dpy19 is a transmembrane domain family whose name is derived from the Caenorhabditis elegans Dumpy mutant.
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