Insulin-Like Peptides: Structure, Signaling, and Function

This chapter discusses the insulin-like peptides: structure, signaling, and function. Insulin-like peptides (ILPs) are paragons for the conservation of hormone structure and function among invertebrates and higher animals. They are encoded by multiple, distinct genes within each species and, upon secretion, serve as hormones, neurotransmitters, and growth factors during post-embryonic life stages. These diverse messages are transduced in target cells through an insulin receptor and a signaling network of activated proteins that directly affect biochemical pathways and gene expression. Of the diverse invertebrate groups, our accumulated knowledge of ILP endocrinology is the deepest and broadest for insects. This knowledge has revealed that essentially all of the proteins that make up the mechanisms for ILP processing, secretion, and signaling are remarkably similar to those of vertebrates, in effect conserving the pleiotropic effects of ILPs between insects and vertebrates.