The soluble proteins of rat seminal vesicle fluid. Some physico-chemical and immunological properties.

The native secretion of rat seminal vesicles was found to contain about 290 mg of protein/ml. The ionic strength of the secretion was low (33 millimho. cm). Some protein (about 13 per cent) precipitated shortly after collection. The soluble proteins were resolved by electrophoresis into four very basic and two minor acidic fractions. Three of the proteins were eluted from a Sephadex G-200 column at a position indicating a molecular weight much in excess of 150,000 daltons; the others were eluted at a position intermediate between IgG and bovine serum albumin (BSA) markers. Ten bands were resolved in polyacrylamide gel electrophoresis following dissociation of the soluble proteins into subunits. Eight of these had molecular weights ranging between 18,500 and 100,000 Daltons. Antisera raised in rabbits against seminal vesicle fluid (SVF) formed, in immunoelectrophoresis (IE) six precipitin bands with SVF. They did not react at all with rat serum proteins, nor did antiserum to rat serum proteins react with SVF. A small amount of rat serum proteins was, however, detected by radioimmunoassay in the insoluble fraction.