What is Insulin-like growth factor 2 (IGF-2)?

IGF-1's imprinted sibling — the dominant growth factor before birth. Structurally it is Single-chain growth factor (67 aa).

How strong is the evidence for IGF-2?

PeptideHormone grades IGF-2 at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.

What is the half-life of IGF-2?

The reported circulating half-life of IGF-2 is Short when free; extended in IGFBP/ALS ternary complexes.

Insulin-like growth factor 2IGF-2

IGF-1's imprinted sibling — the dominant growth factor before birth.

EndogenousEstablished

The other insulin-like growth factor, and the one the body built a whole receptor to take back — knowing how to withdraw a signal is as designed as knowing how to send it.

Identity

Class: Single-chain growth factor (67 aa)
Source: Liver and many tissues; highly expressed in fetal life
Receptor: IGF-1R and insulin receptor isoform A (IR-A); cleared by the IGF-2/M6P receptor

Key properties

Evidence floorClinicalREF1CLIN1

Molecular weight

~7,471 Da

REF

Half-life (native)

Short when free; extended in IGFBP/ALS ternary complexes

CLIN

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

IGF-2 is the principal driver of fetal growth and is the more abundant of the two IGFs in adult human serum. It signals for growth through IGF-1R and, distinctively, through the insulin receptor's A isoform. A third receptor — the IGF-2/mannose-6-phosphate receptor — does not signal at all: it binds IGF-2 and routes it for degradation, acting as a clearance valve on how much is available.

Reference notes

IGF2 is an imprinted gene expressed almost exclusively from the paternal allele; losing that imprinting drives overgrowth syndromes and is common in cancer.
Unlike IGF-1, IGF-2 is a high-affinity ligand for insulin receptor isoform A — a route to growth signalling that bypasses IGF-1R.
Its dedicated 'receptor,' the mannose-6-phosphate receptor, is a non-signalling sink that clears IGF-2 rather than relaying it — buffering a tumour can overwhelm to cause hypoglycaemia.

Common questions

What is Insulin-like growth factor 2 (IGF-2)?: IGF-1's imprinted sibling — the dominant growth factor before birth. Structurally it is Single-chain growth factor (67 aa).
How does IGF-2 work?: IGF-2 is the principal driver of fetal growth and is the more abundant of the two IGFs in adult human serum. It signals for growth through IGF-1R and, distinctively, through the insulin receptor's A isoform. A third receptor — the IGF-2/mannose-6-phosphate receptor — does not signal at all: it binds IGF-2 and routes it for degradation, acting as a clearance valve on how much is available.
How strong is the evidence for IGF-2?: PeptideHormone grades IGF-2 at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of IGF-2?: The reported circulating half-life of IGF-2 is Short when free; extended in IGFBP/ALS ternary complexes.

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.IGF2: Development, Genetic and Epigenetic Abnormalities · Cells, 2022 · PMID 35741015
2.Insulin-like growth factor 2 in development and disease: a mini-review · Gerontology, 2013 · PMID 23257688
3.Insulin-like growth factor-2/mannose-6 phosphate receptors · Vitamins and hormones, 2009 · PMID 19251055