Melittin stimulates Na entry, Na-K pump activity and DNA synthesis in quiescent cultures of mouse cells.

Melittin, an amphipatic polypeptide, increases several fold the activity of Na-K pump in quiescent Swiss 3T3 cells. As with other growth factors, melittin increases the activity of the pump by increasing Na entry into the cell. In contrast, other early responses are not elicited by the toxin. At concentrations that promote ion fluxes, melittin stimulates DNA synthesis in quiescent mouse cells acting synergistically with insulin, epidermal growth factor and with the growth factor released by SV40 BHK cells. In contrast, melittin does not interact synergistically with either phorbol esters of vasopressin. The cellular effects of melittin are consistent with the proposal that ion fluxes signal the initiation of mitogenesis in quiescent cells.