<unk>  are two closely related protein complexes that have almost directly opposite biological effects. Identified in 1986,<unk>  enhances FSH biosynthesis and secretion, and participates in the regulation of the menstrual cycle. Many other functions have been found to be exerted by<unk> , including roles in cell proliferation, differentiation, apoptosis, metabolism, homeostasis, immune response, wound repair, and endocrine function. Conversely,<unk>  downregulates FSH synthesis and<unk> s FSH secretion. The existence of<unk>  was hypothesized as early as 1916; however, it was not demonstrated to exist until Neena Schwartz and Cornelia Channing's work in the mid 1970s, after which both proteins were molecularly characterized ten years later.<unk>  is a dimer composed of two identical or very similar beta subunits.<unk>  is also a dimer wherein the first component is a beta subunit similar or identical to the beta subunit in<unk> . However, in contrast to<unk> , the second component of the<unk>  dimer is a more distantly-related alpha subunit.<unk> ,<unk>  and a number of other structurally related proteins such as anti-Müllerian hormone, bone morphogenetic protein, and growth differentiation factor belong to the TGF-β protein superfamily.
Activin and inhibin
Estrone/progesterone/testosterone
Estradiol/progesterone
Estrone/progesterone
SUSPUP and SUSPPUP
Estradiol/estrone/estriol
UPMC Central Pa
IPP-SHR