Involved in the attachment of the Gal residue on the third xylosyl unit within the XXXG core structure of xyloglucan, the principal glycan that interlaces the cellulose microfibrils in plant cell wall. Interacts with actin and is required for the proper endomembrane organization and for the cell elongation (By similarity). Protein modification; protein glycosylation. The cytoplasmic N-terminal domain interacts with actin, while the lumenal C-terminal domain contributes to the activity of xyloglucan galactosyltransferase. Belongs to the glycosyltransferase 47 family.