title: Characterization of an acidic glycoprotein secreted by principal cells of the rat epididymis.
abstract: 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.
mesh_terms: 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
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D006023:Glycoproteins