Mastoparan acetate is a peptide toxin from wasp venom. It has the chemical structure Ile-Asn-Leu-Lys-Ala-Leu-Ala-Ala-Leu-Ala-Lys-Lys-Ile-Leu-NH2.

Mastoparan has an amphiphilic nature and is reported to exert a variety of pharmacological and biochemical effects. Mastoparan induces exocytosis of hormones from anterior pituitary cells. Mastoparan stimulation of prolactin secretion is dose-dependent, time-dependent, reversible and required the presence of calcium. Mastoparan causes translocation of protein kinase C activity from a soluble to a membrane-attached form. Mastoparan is able to increase the intracellular Ca2+ concentration in Fura-2-loaded individual lactotrophs. Mastoparan is also able to interact with GTP-bindmg proteins. Thus, Mastoparan has been shown to facilitate exchange of nucleotides and to stimulate GTPase activity on G-proteins. It has therefore been proposed that the cellular effects of Mastoparan are due to an ability to mimic G-protein-linked agonist-liganded receptors[1].