Insulin-like Growth Factor 1 (IGF-1)

También conocido como: 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.

Structurally, IGF-1 is a 70-amino-acid single-chain polypeptide with roughly 50% homology to insulin, so correct molecular weight and sequence identity matter when verifying a research reagent — closely related growth factors and engineered analogs can otherwise be confused. In circulation most IGF-1 is not free but bound to a family of six IGF-binding proteins (IGFBP-1 through IGFBP-6) that regulate its half-life and how much ligand reaches the receptor, a key consideration when IGF-1 is added to serum-containing culture media.

At the receptor, IGF-1 activates the IGF-1 receptor tyrosine kinase and its two principal downstream cascades — PI3K/Akt, associated with cell survival and protein synthesis, and Ras/MAPK, associated with proliferation — which is why it remains such a widely used reference ligand in signaling and cell-proliferation research.