John Lattimer lecture. Lipokinins: novel phospholipase A2 activators mediate testosterone effects on embryonic...

Testosterone-treated calf thymocytes produce increased amounts of proteins, termed lipokinins, that stimulate phospholipase A2 from snake venom and mammalian tissue. The induction of these proteins by testosterone is blocked by cycloheximide and, thus, requires new protein synthesis. These proteins activate phospholipase A2 stoichiometrically. They are inactivated by boiling, trypsin or alkaline phosphatase but not by deoxyribonuclease or ribonuclease. Lipokinins significantly repair the failure of masculinization in the Tfm mouse with an X-linked deficiency of androgen-receptor. Thus, the post-receptor effects of testosterone on embryonic genitalia may be mediated through stimulation of phospholipase A2 by lipokinins. Moreover, lipokinins may be involved as stimulators of the arachidonic acid cascade, as lipocortins are inhibitors.