This domain can be found in the C-terminal region of phosphatidylglycerol lysyltransferase mprF, which catalyses the transfer of a lysyl group from L-lysyl-tRNA(Lys) to membrane-bound phosphatidylglycerol (PG), which produces lysylphosphatidylglycerol (LPG). This domain can also be found in lysylphosphatidylglycerol biosynthesis bifunctional protein LysX, which is the two-domain lysyl-transferase (mprF)-lysyl-tRNA synthetase (lysU) protein is responsible for LPG production.