Molecular cloning of complementary deoxyribonucleic acid for an androgen-regulated epididymal protein: sequence homology with metalloproteins

Acidic epididymal glycoprotein (AEG) is a 31,000 molecular weight secretory protein of the rat epididymis. Screening of a rat epididymal cDNA library with affinity-purified AEG antiserum yielded cDNA for AEG. Identity of the clones was verified by comparison of amino acid sequence of the purified protein with the sequence derived from the nucleotide sequence of the cDNA isolates. Two classes of AEG cDNA, approximately 1500 base pairs (bp) and 950 bp in length, differed by 538 bp in the 3'-untranslated region and by four single nucleotide mismatches, one of which was in the coding region. Northern blot hybridization of epididymal RNA revealed two species of AEG mRNA, corresponding in length to each type of cDNA. Analysis of RNA from individual animals provided evidence that the two mRNA species are the products of allelic genes. In vivo studies demonstrated that the level of total AEG mRNA is regulated by androgen. Amino acid sequence homology of AEG with metal-binding domains of several proteins suggests that AEG is a metalloprotein.