Involved in the biosynthesis of sulfolipids in the chloroplast. Catalyzes the first committed step in sulfolipid biosynthesis. Converts glucose 1-phosphate to UDP-glucose, the precursor of the polar head of sulfolipid. In addition to glucose 1-phosphate, can use galactose 1-phosphate, but with much lower activity. No uridyltransferase activity with other hexose monophosphates. Specific for UTP and cannot use ATP, CTP, and GTP. alpha-D-glucose 1-phosphate + H(+) + UTP = diphosphate + UDP-alpha-D-glucose Inhibited by pyrophosphate. Induced by phosphate starvation. Belongs to the UDPGP type 1 family.