Characterization of the Receptor for Insulin-like Growth Factor on Leishmania Promastigotes

Abstract

Gomes, C. M. C., Goto, H., Magnanelli, A. C., Monteiro, H. P., Soares, R. P. S., Corbett, C. E. P., and Gidlund, M. 2001. Characterization of the receptor for insulin-like growth factor on Leishmania promastigotes. Experimental Parasitology99, 190–197. Insulin-like growth factor (IGF)-I constitutively present in the skin is one of the first growth factors that Leishmania parasites encounter after transmission to the vertebrate host. We have previously shown that IGF-I is a potent growth-promoting factor for Leishmania parasites. IGF-I binds specifically to a single-site putative receptor at the parasite membrane, triggering a cascade of phosphorylation reactions. In the present article we characterize the receptor for IGF-I on Leishmania (Leishmania) mexicana promastigotes. The receptor is a monomeric glycoprotein with a molecular mass of 65 kDa and is antigenically related to the α chain of human type 1 IGF-I receptor. Upon IGF-I stimulation the receptor undergoes autophosphorylation on tyrosine residues with activation of its signaling pathway. Activation of the IGF-I receptor also leads to phosphorylation of an 185-kDa molecule that is homologous to the substrate of the insulin receptor present in human cells, the insulin receptor substrate 1 (IRS-1).