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Secrétana as [[célula de Sertoli|células de Sertoli]] dos [[túbulo seminífero|túbulos seminíferos]] dos [[testículo]]s <ref>{{cite journal |author=Skinner M, McLachlan R, Bremner W |title=Stimulation of Sertoli cell inhibin secretion by the testicular paracrine factor PModS |journal=Mol Cell Endocrinol |volume=66 |issue=2 |pages=239–49 |year=1989 |pmid=2515083 |doi=10.1016/0303-7207(89)90036-1}}</ref>. Os [[andróxeno]]s estimulan a produción de inhibina; esta [[proteína]] pode tamén contribuír a regular localmente a [[espermatoxénese]].
== MechanismMechanismo ofde actionacción ==
Non se comprende aínda ben o mecanismo de acción da inhibina, pero pode implicar a competencia coa [[activina]] para unirse aos receptores da activina e/ou unirse a receptores específicos da inhibina.<ref name="pmid15027884"/>
=== Activin ===
As with other members of the superfamily, activins interact with two types of cell surface [[transmembrane receptor]]s (Types I and II) which have intrinsic [[Serine/threonine-specific protein kinase|serine/threonine kinase]] activities in their cytoplasmic domains:
* [[Activin type 1 receptors]]: [[ACVR1]], [[ACVR1B]], [[ACVR1C]]
* [[Activin type 2 receptors]]: [[ACVR2A]], [[ACVR2B]]
Activin binds to the Type II receptor and initiates a cascade reaction that leads to the recruitment, phosphorylation, and activation of Type I activin receptor. This then interacts with and then phosphorylates [[Mothers against decapentaplegic homolog 2|SMAD2]] and [[Mothers against decapentaplegic homolog 3|SMAD3]], two of the cytoplasmic [[R-SMAD|SMAD]] proteins.
Smad3 then translocates to the nucleus and interacts with [[Mothers against decapentaplegic homolog 4|SMAD4]] through multimerization, resulting in their modulation as [[transcription factor]] complexes responsible for the expression of a large variety of genes.
=== Inhibin ===
In contrast to activin, much less is known about the mechanism of action of inhibin, but may involve competing with activin for binding to activin receptors and/or binding to inhibin-specific receptors.<ref name="pmid15027884"/>
== Clinical significance ==
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