Studies on pituitary follitropin. IV. A conformation specific radioimmunoassay for the ovine hormone.

An antiserum to partially purified ovine follitropin (50 x NIH-FSH-S10) shows species specificity. It is conformation dependent and requires the proper recombination of the alpha and beta subunits for maximal reactivity. The isolated alpha subunit is essentially inactive and the hormone specific beta subunit is weakly reactive. The homologous radioimmunoassay is valuable for estimating native ovine follitropin in the presence of free subunits. It also provides a sensitive method to study association-dissociation and structure-function relationships.