In invertebrates, insulin related peptides (IRPs) and their receptors play a crucial role in reproduction, nutrient metabolism, and lifespan. A search of the completed Anopheles gambiae genome revealed five IRP genes, each encoding a preproinsulin consisting of a signal peptide, an A and B chain, and a C-peptide flanked by proteolytic processing sites. IRPs 1-4 are clustered on chromosome three, and most closely resemble mammalian insulins and Drosophila IRPs 1-5. The fifth IRP possesses an additional amino acid between two key cysteine residues in the A chain, a variation observed in other invertebrates. Although multiple IRP copies typically are found in invertebrate genomes, a single insulin receptor is present, the same as in An. gambiae. The insulin receptor gene in An. gambiae encodes a proreceptor consisting of two subunits, an extracellular a subunit involved in ligand binding and a transmembrane b subunit with an intracellular tyrosine kinase domain. We used RT-PCR and immunoassays to determine the expression pattern of the IRP and receptor genes in all developmental stages and adult tissues from An. gambiae.
Species 1: Diptera Culicidae Anopheles gambiae (African malaria mosquito)
Keywords: peptide hormone, signal transduction
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