Predicted to enable ATPase binding activity and mannosyltransferase activity. Predicted to be involved in protein O-linked mannosylation. Predicted to act upstream of or within several processes, including endoplasmic reticulum unfolded protein response; outer hair cell apoptotic process; and positive regulation of endoplasmic reticulum calcium ion concentration. Predicted to be located in endoplasmic reticulum. Orthologous to human TMTC4 (transmembrane O-mannosyltransferase targeting cadherins 4). [provided by Alliance of Genome Resources, Apr 2022]