Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase-like protein MGAT4D (Mgat4d)

Isoform 2: May play a role in male spermatogenesis. In vitro acts as inhibitor of MGAT1 activity inducing cell surface proteins to carry mainly substantial mannose N-glycans.

The function is mediated by its lumenal domain and occurs specifically in the Golgi. A catalytic glucosyltransferase activity isn't detected.