Sucrose-cleaving enzyme that provides UDP-glucose and fructose for various metabolic pathways. an NDP-alpha-D-glucose + D-fructose = a ribonucleoside 5'-diphosphate + H(+) + sucrose Homotetramer. Phosphorylated on serine residue(s). Belongs to the glycosyltransferase 1 family. Plant sucrose synthase subfamily.