QUANTITATIVE-DETERMINATION OF SPECIFIC PROTEINS IN RAT EPIDIDYMIS

This paper describes the development of a radioimmunoassay for the measurement of specific proteins (SEP) in rat epididymis. Using [125I]-SEP the assay is useful within the range 0.6-30 ng SEP. With this method we confirmed the organ specificity of SEP which could neither be detected in the cytosol of several other organs in the rat nor in rat blood plasma. Furthermore, SEP appear to be species specific since the epididymal cytosol from man, stallion, bull, dog and rabbit did not react with serum anti rat SEP. Castration decreased the SEP content of rat epididymis. Preincubation of anti-SEP with cauda epididymis spermatozoa sharply decreased the binding capacity of the antiserum. The same treatment did not alter the binding capacity of control anti-LH serum. Immunofluorescence experiments show that SEP are attached to spermatozoa obtained from the cauda epididymis. © 1979.