This is a family of alpha-1,2 mannosyl-transferases involved in N-linked and O-linked glycosylation of proteins. Some of the enzymes in this family have been shown to be involved in O- and N-linked glycan modifications in the Golgi [1].

1: The KTR and MNN1 mannosyltransferase families of Saccharomyces cerevisiae. Lussier M, Sdicu AM, Bussey H. Biochim Biophys Acta 1999;1426:323-334. PMID:9878809