Activin and inhibin

<p>Activin and inhibin are two closely related <a href="/facts/Protein/Jxmagu3E">protein</a> <a href="/facts/Multiprotein_complex/GW11Ee34">complexes</a> that have almost directly opposite biological effects. Identified in 1986, activin enhances <a href="/facts/Follicle-stimulating_hormone/n6CwdebD">FSH</a> <a href="/facts/Biosynthesis/aFk7Tk7f">biosynthesis</a> and <a href="/facts/Secretion/VHk9eLAV">secretion</a>, and participates in the regulation of the <a href="/facts/Menstrual_cycle/AY6Y9xxM">menstrual cycle</a>. Many other functions have been found to be exerted by activin, including roles in cell proliferation, <a href="/facts/Cellular_differentiation/bCVqUG7w">differentiation</a>, <a href="/facts/Apoptosis/8dVzSm4y">apoptosis</a>, <a href="/facts/Metabolism/WxDrm8k5">metabolism</a>, <a href="/facts/Homeostasis/rloTGAHa">homeostasis</a>, <a href="/facts/Immune_system/HRCTf1pb">immune response</a>, <a href="/facts/Wound_healing/3NlzV5Qn">wound repair</a>, and <a href="/facts/Endocrine_system/PDvN5cpj">endocrine</a> function. Conversely, inhibin downregulates FSH synthesis and inhibits FSH secretion. The existence of inhibin was hypothesized as early as 1916; however, it was not demonstrated to exist until <a href="/facts/Neena_Schwartz/rJ4E3Hyo">Neena Schwartz</a> and <a href="/facts/Cornelia_Channing/DIJQ5k24">Cornelia Channing</a>'s work in the mid-1970s, after which both proteins were molecularly characterized ten years later.
</p><p>Activin is a <a href="/facts/Protein_dimer/c8LwFJPG">dimer</a> composed of two identical or very similar beta subunits. Inhibin is also a dimer wherein the first component is a beta subunit similar or identical to the beta subunit in activin. However, in contrast to activin, the second component of the inhibin dimer is a more distantly-related alpha subunit. Activin, inhibin and a number of other structurally related proteins such as <a href="/facts/Anti-M%C3%BCllerian_hormone/P4zTofK4">anti-Müllerian hormone</a>, <a href="/facts/Bone_morphogenetic_protein/VpwFr7Ih">bone morphogenetic protein</a>, and <a href="/facts/Growth_differentiation_factor/3m9gBa1X">growth differentiation factor</a> belong to the <a href="/facts/Transforming_growth_factor_beta_superfamily/3n4xLA7r">TGF-β protein superfamily</a>.
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Activin and inhibin open-in-new

Activin and inhibin