Electrofocusing fractionation and characterization of pituitary follicle-stimulating hormone from male and female rats.
Extracts of male and female rat pituitaries were fractionated by electrofocusing on sucrose density gradients and the pH distribution of FSH determined by an FSH in vitro bioassay, rFSH radioimmunoassay (RIA) and FSH radioreceptor assay (RRA) method. FSH for both sexes was located in the pH range 3-6. Significantly more activity, as measured by all three methods, was found in the male in the pH range 3.4-4.0 (P less than 0.01), while conversely significantly more activity was found in the female in the pH range 4.8-6.0 (P less than 0.05). Ratios of the levels of FSH assayed by the three methods showed significant (P less than 0.05) differences between sexes in both the original pituitary extracts and electrofocusing fractions in the pH region 4.4-6.0. The acidic fractions, when fractionated by gel filtration (Sephadex G100SF), were larger in apparent molecular size than the more alkaline fractions found in pituitary extracts from either sex. Binding of electrofocusing fractions from male pituitaries to concanavalin A showed significant (P less than 0.01) differences between fractions, suggesting that the various FSH fractions may differ in their carbohydrate structure. It is concluded that the differences in apparent size and charge of FSH from male and female rat pituitaries can be attributed to the combination in different proportions of the various FSH species. However, differences in the ratio of FSH activity (in vitro bioassay, RRA and RIA) for FSH from the same pI region (pH 4.4-6.0) between sexes suggests that structural differences may also exist.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002850:Chromatography, Gel; D005260:Female; D005640:Follicle Stimulating Hormone / Q000302:isolation & purification*; D007525:Isoelectric Focusing; D008297:Male; D008968:Molecular Conformation; D010902:Pituitary Gland / Q000032:analysis*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors
D005640:Follicle Stimulating Hormone