IGF-2 belongs to the insulin-like growth-factor family, but it needs its own evidence record. The number in its name does not restrict it to a receptor with the same number, and an inherited gene copy does not necessarily make the same contribution as the copy from the other parent. These distinctions explain much of the apparent complexity in IGF-2 research.
Use the mature chain as a molecular reference
Torres and colleagues’ human IGF-2 solution structure is deposited as PDB 1IGL. Its record contains one unmutated 67-residue chain and an ensemble of 20 submitted NMR conformers.Torres and colleagues — Human IGF-II solution structure, PDB 1IGL (opens in a new tab)
The ensemble represents alternative models consistent with the structural data, rather than 20 different peptide ingredients. The paper identified regions that were better defined than others, so a single selected drawing should not imply identical precision throughout the molecule.Torres and colleagues — Human IGF-II solution structure, PDB 1IGL (opens in a new tab)
For a sequence comparison, use the defined mature chain and state whether the other record is also a mature peptide. Comparing that chain directly with an unprocessed precursor would introduce extra sequence by changing the object being compared.
The family relationship to IGF-1 is useful for finding related literature. It does not substitute for checking IGF-2-specific experiments, especially where a binding partner recognises a particular molecular surface.
Do not match ligand and receptor by number alone
Frasca and colleagues studied IGF-II interactions with insulin-receptor isoforms A and B, which differ through alternative splicing. In their experimental systems, isoform A bound IGF-II much more strongly than isoform B, with affinity comparable to the IGF-I receptor.Frasca and colleagues — Insulin receptor isoform A as an IGF-II receptor (opens in a new tab)
The study included engineered mouse cells expressing human receptor isoforms. IGF-II and insulin also produced different balances of proliferation-related and metabolic readouts through isoform A under those conditions.Frasca and colleagues — Insulin receptor isoform A as an IGF-II receptor (opens in a new tab)
This is receptor- and system-specific evidence. It does not establish that every cell responds in the same way, or that a ligand can be assigned one universal effect independent of the receptors present.
| Field | What to write |
|---|---|
| Ligand | IGF-II, with the tested molecular form |
| Receptor | The named receptor and relevant isoform |
| System | Engineered cells, primary tissue or another defined model |
| Readout | Binding, receptor activation or a downstream response |
A receptor called type 1 can therefore appear in an IGF-2 paper without a naming error. The actual interaction evidence is more informative than matching numerals.
Read parent-of-origin findings with their exceptions
DeChiara, Robertson and Efstratiadis disrupted the mouse Igf2 gene and compared inheritance from each parent. Heterozygous animals showed impaired growth when the disrupted copy came from the father, but not when it came from the mother.DeChiara, Robertson and Efstratiadis — Parental imprinting of the mouse Igf-2 gene (opens in a new tab)
The authors found paternal expression in the embryos they examined, with exceptions in the choroid plexus and leptomeninges where both copies were active. Those exceptions belong with the finding, rather than being erased by a universal paternal-only slogan.DeChiara, Robertson and Efstratiadis — Parental imprinting of the mouse Igf-2 gene (opens in a new tab)
The experiment concerns gene expression and development in mice. It does not mean that the mature peptide carries a different amino-acid sequence simply because the expressed gene copy came from one parent.
Avoid borrowing conclusions from neighbouring fields
An IGF-2 reference can connect structural biology, receptor experiments and developmental genetics without pretending that they answer one clinical question. Each supplies a different part of the explanation.
If a claim concerns a particular tissue response, look for the matching receptor context and a direct functional measurement. If it concerns inherited expression, look for allele-specific evidence in the relevant species and tissue.
For any proposed intervention, neither a structural model nor a gene-expression pattern establishes benefit on its own. That claim needs an intervention study with the exact substance, population and outcome.
Keeping these boundaries makes the literature easier to navigate: IGF-1 provides a related comparison, while IGF-2 retains its own molecular and experimental identity. This article is a research reference, not guidance on administering growth factors.
Sources and further detail
- Torres and colleagues — Human IGF-II solution structure, PDB 1IGL (opens in a new tab)
Original deposition, 67-residue identity, 20-conformer ensemble and paper abstract checked. No claim that all regions have equal structural precision.
- Frasca and colleagues — Insulin receptor isoform A as an IGF-II receptor (opens in a new tab)
Original 1999 abstract and figure descriptions read, including engineered-cell identity. Binding and downstream effects remain conditional on the tested system.
- DeChiara, Robertson and Efstratiadis — Parental imprinting of the mouse Igf-2 gene (opens in a new tab)
Original indexed 1991 abstract read. Paternal transmission result and choroid-plexus/leptomeningeal exceptions preserved; not extrapolated to all human tissues.
Sources checked 19 September 2026. Worked examples are illustrative unless a supplied report is explicitly identified. This article has not undergone independent scientific peer review.