FIGURE 1.

Classifications of PLDs. A, phospholipase D enzymes with HKD domains and intact lipase activity. B, phospholipase D enzymes with HKD domains that lack lipase activity. C, phospholipase D enzymes that lack HKD domains but are dependent on divalent cations for action. Parts of this panel are based on Ref. 99. Abbreviations: Phospholipase D activity, lipid phosphodiesterase toward PC (also phosphatidylethanolamine, phosphatidylserine, and cardiolipin) releasing PA and polar head; Ce, Caenorhabditis elegans; Dm, Drosophila melanogaster; Dr, Danio rerio; MLS, mitochondrial localization signal; mPLD5, mouse PLD5; sc, Streptomyces chromofuscus; GPI, glycosyl phosphatidyl inositol. Red boxes marked with TM, transmembrane domains; black boxes, HKD motifs (HXKX₄DX₆GSXN); yellow box, C2 domain.