Characterization of the secretory proteins of rat preputial gland in relation to urinary proteins.
The water-soluble proteins of the rat preputial gland secretion were characterized in native and SDS-treated form on polyacrylamide gel electrophoresis. Nine major proteins were present in the secretion. One protein was a glycoprotein of molecular weight greater than 200,000 with beta-glucuronidase activity, and the other eight proteins had a molecular weight of 17,000, but with different charges. Acid phosphatase and arylsulphatase activities were present in the secretion in minor amounts. The isoelectric points of the secretory proteins ranged from 8.5 to 5.3; none of the proteins were lipoproteins, and there were no sex differences. The male and female rat urinary proteins were also characterized electrophoretically. The male rats had two different protein patterns, probably genetically determined. The female rats showed basically one urinary protein pattern, but their urines were frequently mixed with the preputial gland secretory proteins, which most likely played a part in the chemical communication. The mixing could not be correlated to daytime or estrous cycle.