Insulin-like growth factor 1IGF-1

The hepatic mediator of growth hormone's anabolic effects.

EndogenousEstablished

Identity

Class: Single-chain growth factor (70 aa)
Source: Liver (GH-stimulated) and local tissues
Receptor: IGF-1 receptor (IGF-1R, a receptor tyrosine kinase)

Key properties

Molecular weight

~7,649 Da

Half-life (native)

~12–16 h bound to IGFBPs (~10 min free)

Model dosing

Approximate values for the native hormone. Engineered analogs are often deliberately larger and far longer-acting.

Mechanism

GH stimulates hepatic IGF-1, which carries out much of GH's tissue-growth effect and feeds back negatively on the pituitary and hypothalamus to restrain further GH release. IGF-1 circulates bound to IGF-binding proteins that modulate its availability.

Reference notes

IGF-1 is the principal effector of GH's growth-promoting actions.
Its negative feedback is why sustained secretagogue exposure does not produce limitless GH.
IGF-binding proteins are a key layer controlling how much IGF-1 is bioavailable.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

1.Regulation and function of insulin and insulin-like growth factor receptor signalling · Nature reviews. Molecular cell biology, 2025 · PMID 39930003
2.Insulin-Like Growth Factor-1 and Neuroinflammation · Frontiers in aging neuroscience, 2017 · PMID 29163145