IGF-1 DES

IGF-1 DES (Des(1-3) IGF-1) is a truncated variant of insulin-like growth factor 1 (IGF-1) in which the first three N-terminal amino acids (Gly-Pro-Glu) have been removed. This truncation is significant because the N-terminal region of IGF-1 is the primary binding site for IGF-binding proteins (IGFBPs), particularly IGFBP-3, which binds approximately 75-80% of circulating IGF-1 in a ternary complex with acid-labile subunit (ALS). By removing the IGFBP-binding domain, IGF-1 DES exhibits dramatically reduced affinity for IGFBPs, resulting in a significantly higher proportion of free (bioavailable) peptide available for IGF-1 receptor (IGF1R) engagement. The IGF-1 receptor is a heterotetrameric receptor tyrosine kinase that, upon ligand binding, undergoes autophosphorylation and activates the PI3K/Akt and MAPK/ERK signalling cascades — pathways that drive cell proliferation, survival (anti-apoptosis), and differentiation. In muscle tissue, IGF-1 receptor activation stimulates satellite cell activation, myoblast proliferation, and myotube hypertrophy. The increased bioavailability of IGF-1 DES means that, at equivalent molar doses, it produces more potent receptor activation than full-length IGF-1, as less of the peptide is sequestered by IGFBPs. The des(1-3) truncation does not alter the receptor-binding domain, so IGF-1 DES maintains full affinity for the IGF-1 receptor while gaining enhanced bioavailability.