[Analysis of the human acidic epididymal glycoprotein-like molecule: isolation of cDNA and tissue localization]

Acidic epididymal glycoprotein (AEG) is an androgen-dependent, epididymal secretory protein assumed to play a major role in sperm maturation. In the present study, we isolated cDNA clones encoding the human AEG-like molecule and determined their nucleotide sequences. The deduced human AEG-like molecule was made up of 230 amino acids, excluding a signal peptide, and contained one potential N-linked glycosylation site. All cysteinyl residues were conserved between the human AEG-like molecule and the AEG molecules of rats and mice. The human AEG-like molecule was equally similar to the AEG molecules of rats and mice and a related testis-specific protein known as TPX1 of human and mice (approximately 40% amino acid sequence similarity). Northern blot analysis showed that the human AEG-like gene is expressed specifically in the epididymis. To identify the product of the human AEG-like gene, polyclonal antibody was produced by immunizing rabbits with a recombinant human AEG-like protein expressed in E. coli. This antibody detected a major band of 30 kD and a minor band of 26 kD in the caput, corpus, and cauda regions of the epididymis, the ductus deferens, the sperm, and the seminal plasma. Immunohistochemical analysis showed that the human AEG-like molecule is located in the lumen and epithelium of distal ductus efferentes and epididymal ducts, and on the postacrosomal region of the sperm head.