Catalyzes the transfer of the diacylglyceryl group from phosphatidylglycerol to the sulfhydryl group of the N-terminal cysteine of a prolipoprotein, the first step in the formation of mature lipoproteins. 1,2-diacyl-sn-glycero-3-phospho-(1'-sn-glycerol) + L-cysteinyl-[prolipoprotein] = H(+) + S-1,2-diacyl-sn-glyceryl-L-cysteinyl-[prolipoprotein] + sn-glycerol 1-phosphate Protein modification; lipoprotein biosynthesis (diacylglyceryl transfer). Belongs to the Lgt family.