Functional correlates of the growth factor structure of pituitary follitropin

393-401<span style="font-size:14.0pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:#0f0f0f;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="">Pituitary follitropin (FSH) is an important member of the glycoprotein hormone family that is required for maintenance of reproductive functions. The hormone has been visualized as having motifs such as the cystine knots that are typical of other growth factors with mitogenic functions. By studying its receptor system in the ovary and testis, we have demonstrated the existence of the FSH receptor that has a single transmembrane domain. This receptor functions via a non-cyclic AMP dependent pathway and stimulates Ca2+ mobilization and activation of extracellular activated kinases. Thus its actions are separate from the classical Gs coupled receptor. This constitutes the first functional evidence for the growth factor structure of the hormone. Alternative splicing of a single large FSH-R gene produces all the FSH receptor variants. The polymorphic forms of the hormone might interact differently with these receptors to influence target cell growth patterns and steroidogenic responses.