Characterization of an acidic glycoprotein secreted by principal cells of the rat epididymis.
An acidic protein which is secreted by epididymal epithelial cells, has been characterized with respect to physiochemical properties. Acidic epididymal glycoprotein is a glycoprotein of molecular weight of 31 700. It is apparently a symmetrical molecule (f/f0 = 1.26) composed of a single polypeptide chain. Carbohydrate content is 7.5% and consists mainly of hexoses (73%). Acidic epididymal glycoprotein is rich in aromatic amino acids although its content of hydrophobic amino acids (50.9%) and average hydrophobicity (1053 cal/residue) is unexceptional. The acidic nature of acidic epididymal glycoprotein is consistent with a high content of aspartic and glutamic acid (27.5%), a high fractional charge (0.37) and a low isoelectric point (pI = 4.7). Acidic epididymal glycoprotein appears to bind to spermatozoa during epididymal transit and may thus increase the negative charge on the sperm plasma membrane. An increase in anodic mobility is a characteristic change associated with sperm maturation and implies a role for acidic epididymal glycoprotein in this process.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D004822:Epididymis / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism* / Q000502:physiology; D007526:Isoelectric Point; D008297:Male; D008970:Molecular Weight; D051381:Rats; D013079:Sperm Maturation
D000596:Amino Acids; D002241:Carbohydrates; D006023:Glycoproteins