Insulin-like Growth Factor 1 (IGF-1)

Also known as: IGF-1, IGF1, Insulin-like growth factor 1, somatomedin C

IGF-1 is a peptide hormone structurally homologous to insulin that mediates many of growth hormone’s downstream cellular effects. It is produced primarily by the liver following GH-receptor activation and signals through the IGF-1 receptor.

IGF-1 is the principal downstream effector of the growth hormone (GH) axis: GH released by the pituitary stimulates the liver to synthesize and secrete IGF-1, which then acts through the IGF-1 receptor to influence cell proliferation, differentiation, and protein synthesis. This GH–IGF-1 pathway is a central topic in endocrinology and metabolic research.

In vitro, IGF-1 is used as a reference ligand in cell-proliferation and receptor-binding assays studying the GH/IGF-1 signaling axis, including research on GHRH analogs and secretagogues that act upstream of IGF-1 release.

A widely used research analog is IGF-1 LR3 (Long R3 IGF-1) — an engineered variant with a position-3 arginine substitution and a 13-amino-acid N-terminal extension that extend its half-life and reduce binding to IGF-binding proteins, making it a practical tool for receptor and signaling studies.