The Evolution of Cell membranes

Cell membranes are largely composed of phospholipids. Phospholipids in turn are built on a glycerol phosphate. The are two different glycerol phosphates in use, glycerol-1-phosphate (G1P) and glycerol-3-phosphate (G3P). The archaea use G1P and the eubacteria and the eukaryotes use G3P. The two phospholipids are synthesized in entirely different ways. The mystery is, how did two such different systems evolve, and what was the nature of the common ancestor? Compounding the mystery, eukaryote transciption and translation is similiar to the archea, while eukaryote cell membranes are similar to bacteria. See Ancestral lipid biosynthesis and early membrane evolution and archea cell membranes.