This gene encodes an integral membrane protein that belongs to the dolichyl-phosphate-mannose-protein mannosyltransferase family. The encoded enzyme is found in the membrane of the endoplasmic reticulum. This protein is a component of the protein O-mannosyltransferase enzyme complex which is involved in modification of the protein alpha-dystroglycan. Mutations in the human gene are a cause of different forms of muscular dystrophy-dystroglycanopathy (MDDG), type A2 (also known as Walker-Warburg syndrome), type B2 and type C2 (also known as limb-girdle muscular dystrophy). [provided by RefSeq, Sep 2015]