Insulin-like growth factor 2
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Insulin-like growth factor 2 (IGF-2) is one of three protein hormones that share structural similarity to insulin.
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[edit] Gene structure
In humans, the IGF2 gene is located on chromosome 11p15.5, a region which contains numerous imprinted genes. In mice this homologous region is found at distal chromosome 7. In both organisms, Igf2 is imprinted, with expression resulting favourably from the paternally inherited allele.
The protein CTCF is involved in repressing expression of the gene, by binding to the H19 imprinting control region (ICR) along with Differentially-methylated Region-1 (DMR1) and Matrix Attachment Region -3 (MAR3). These three DNA sequences bind to CTCF in a way that limits downstream enhancer access to the Igf2 region. The mechanism in which CTCF binds to these regions is currently unknown, but could include either a direct DNA-CTCF interaction or it could possibly be mediated by other proteins
[edit] Protein structure
IGF-2 exerts its effects by binding to the IGF-1 receptor. IGF2 may also bind to the IGF-2 receptor (also called the cation-independent mannose 6-phosphate receptor), which acts as a signalling antagonist; that is, to prevent IGF2 responses.
[edit] Function
The major role of IGF2 is as a growth promoting hormone during gestation.
[edit] Diseases
It is sometimes produced in non-islet cell tumours, causing hypoglycemia (Doege-Potter syndrome).
[edit] See also
[edit] External links
[edit] References
[edit] Further reading
- O'Dell SD, Day IN (1998). "Insulin-like growth factor II (IGF-II).". Int. J. Biochem. Cell Biol. 30 (7): 767–71. PMID 9722981.
- Butler AA, Yakar S, Gewolb IH, et al. (1999). "Insulin-like growth factor-I receptor signal transduction: at the interface between physiology and cell biology.". Comp. Biochem. Physiol. B, Biochem. Mol. Biol. 121 (1): 19–26. PMID 9972281.
- Kalli KR, Conover CA (2004). "The insulin-like growth factor/insulin system in epithelial ovarian cancer.". Front. Biosci. 8: d714–22. PMID 12700030.
- Wood AW, Duan C, Bern HA (2005). "Insulin-like growth factor signaling in fish.". Int. Rev. Cytol. 243: 215–85. doi:. PMID 15797461.
- Fowden AL, Sibley C, Reik W, Constancia M (2006). "Imprinted genes, placental development and fetal growth.". Horm. Res. 65 Suppl 3: 50–8. doi:. PMID 16612114.
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