Phosphatidylinositol
A. only functions as an intermediate in the biosynthesis of phosphatidylinositol-4 phosphate in eukaryotes
B. does not occur in the membranes of eukaryotes
C. constitutes about 5 % of the phospholipids in prokaryotes
D. may be converted to two phosphatidylinositol derivatives that yield cellular second messengers in animal cells