Mastoparan

Mastoparan, a tetradecapeptide which is a component of wasp venom, stimulates release of prolactin from cultured rat anterior pituitary cells. In Vitro: 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].