Required for the biosynthesis of the tetrasaccharide linkage region of proteoglycans, especially for small proteoglycans in skin fibroblasts. 3-O-(beta-D-xylosyl)-L-seryl-[protein] + UDP-alpha-D-galactose = 3-O-(beta-D-galactosyl-(1->4)-beta-D-xylosyl)-L-seryl-[protein] + H(+) + UDP Protein modification; protein glycosylation. Cis cisternae of Golgi stack. High expression in heart, pancreas and liver, medium in placenta and kidney, low in brain, skeletal muscle and lung. The disease is caused by variants affecting the gene represented in this entry. Belongs to the glycosyltransferase 7 family. Beta-1,4-galactosyltransferase 7