Immunoserological, immunohistochemical and immunobiological studies on an antigenic glycoprotein isolated from human...

The seminal plasma and a fraction of the spermatozoal membrane solubilised by sarkosyl contain similar antigenic determinants. The glycoprotein isolated from the seminal plasma also contains determinants which are immunologically identical to those of the sarkosyl soluble fraction. Three of these determinants were identified as: two oligosaccharide chains with terminal N-acetyl neuraminic acid and with subterminal alpha-L-fucopyranose and beta-D-galactopyranose residues respectively, and an oligosaccharide chain with beta-D-galactopyranose as non-reducing end-chain. The receptors on the spermatozoa to anti-glycoprotein and anti-seminal plasma antibodies are localized. The specificity of the receptors localised in the neck region depends entirely on the presence of N-acetyl neuraminic acid as end-chain group while the specificity of the receptors to the anti-seminal plasma antibodies in the intermediate segment plus tail and to the anti-glycoprotein antibodies in the post-nuclear cap depends also on the subterminal units. At least two other receptors in the equatorial zone are ended by residues different from the N-acetyl neuraminic acid. One of them, which is also found in the acrosome, does not have specificity for anti-glycoprotein antibodies, while the other, which is not in the acrosome, has anti-glycoprotein antibodies specificity and may have a terminal beta-D-galactopyranose residue.