GH-IGF-I axis

<p>IGFs are part of a <a title="Complex system" href="https://en.wikipedia.org/wiki/Complex_system">complex system</a> that cells use to communicate with their <a title="Physiology" href="https://en.wikipedia.org/wiki/Physiology">physiologic</a> environment. This complex system (often referred to as the IGF "axis") consists of two <a class="mw-redirect" title="Cell-surface receptor" href="https://en.wikipedia.org/wiki/Cell-surface_receptor">cell-surface receptors</a>(IGF1R and IGF2R), two <a title="Ligand (biochemistry)" href="https://en.wikipedia.org/wiki/Ligand_(biochemistry)">ligands</a> (<a title="Insulin-like growth factor 1" href="https://en.wikipedia.org/wiki/Insulin-like_growth_factor_1">Insulin-like growth factor 1</a> (IGF-1) and <a title="Insulin-like growth factor 2" href="https://en.wikipedia.org/wiki/Insulin-like_growth_factor_2">Insulin-like growth factor 2</a> (IGF-2)), a family of six high-affinity <a title="Insulin-like growth factor-binding protein" href="https://en.wikipedia.org/wiki/Insulin-like_growth_factor-binding_protein">IGF-binding proteins</a> (IGFBP-1 to IGFBP-6), as well as associated <a title="Insulin-like growth factor-binding protein" href="https://en.wikipedia.org/wiki/Insulin-like_growth_factor-binding_protein">IGFBP</a> degrading <a title="Enzyme" href="https://en.wikipedia.org/wiki/Enzyme">enzymes</a>, referred to collectively as <a title="Protease" href="https://en.wikipedia.org/wiki/Protease">proteases</a>.</p>

<p>From: <a href="https://www.ebi.ac.uk/interpro/entry/IPR022322">Insulin-like growth factor-binding protein 1 (IPR022322) < InterPro < EMBL-EBI</a></p>

<p>Insulin-like growth factors (IGFs)-I and -II are small secreted peptides that stimulate the survival, and promote the proliferation and differentiation, of many cell types [<a id="1" class="ext" href="http://europepmc.org/abstract/MED/8874492">PMID: 8874492</a>]. In biological fluids, these growth factors are usually bound to IGF binding proteins (IGFBPs), which regulate their availability and activity by prolonging their half-life and modulating their receptor interactions.</p>

<p>To date, six IGFBP family members have been identified (termed IGFBP1-6) [<a id="2" class="ext" href="http://europepmc.org/abstract/MED/10605625">PMID: 10605625</a>]. They share a conserved gene (intron-exon) organisation and high IGF binding affinity. Structurally, the proteins also share a common domain architecture, possessing a conserved N-terminal IGFBP domain, a highly variable mid-section, and a thyroglobulin type-1 (Tg1) domain in their C-terminal regions.</p>

<p>In addition to their role in the regulation of IGF activity, there is evidence for the direct association of IGFBPs with a variety of extracellular and cell surface molecules [<a id="3" class="ext" href="http://europepmc.org/abstract/MED/7504671">PMID: 7504671</a>, <a id="4" class="ext" href="http://europepmc.org/abstract/MED/7499327">PMID: 7499327</a>], with consequent effects upon important biological processes. These include modulation of bone cell proliferation [<a id="5" class="ext" href="http://europepmc.org/abstract/MED/7544787">PMID: 7544787</a>], and growth arrest of breast and prostate cancer cells [<a id="6" class="ext" href="http://europepmc.org/abstract/MED/7504671">PMID: 7504671</a>, <a id="7" class="ext" href="http://europepmc.org/abstract/MED/9115291">PMID: 9115291</a>].</p>

<p>IGFBP1 (also known as amniotic fluid binding protein (AFBP) and placental protein-12) is involved in the regulation of foetal growth: there is a strong inverse correlation between circulating IGFBP1 levels and foetal size [<a id="8" class="ext" href="http://europepmc.org/abstract/MED/7505470">PMID: 7505470</a>]. It also functions as a survival factor and pro-regeneration factor in the liver [<a id="9" class="ext" href="http://europepmc.org/abstract/MED/12511596">PMID: 12511596</a>].</p>

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<p><a class="ext" href="http://www.ebi.ac.uk/QuickGO/term/GO:0005520">GO:0005520</a> insulin-like growth factor binding </p>

<h4>Cellular Component</h4>

<p><a class="ext" href="http://www.ebi.ac.uk/QuickGO/term/GO:0005576">GO:0005576</a> extracellular region </p>

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