Molecular cloning of two cDNAs for related secretory proteins in lizard epididymis: gene expression during androgen-induced cell growth and secretion.

Lizard epididymis is an androgen-dependent tissue which produces notably ten related secretory proteins (L-proteins, Mr 19,000) during the reproductive period. These proteins were synthesized in vitro as preproteins (Mr 25,000, 24,000, 23,500). A cDNA library in the plasmid pBr322 was constructed and two cDNA clones were isolated by differential hybridization according to the differential expression of the mRNAs in stages 1 and 6 of the annual reproductive cycle. Translations of mRNAs hybrid-selected by two clones (LV123, LV132) yielded proteins which were immunoprecipitated by the L-antiserum. These preproteins were processed in vitro into six peptides; four were encoded by mRNAs selected with the LV123 clone, the others by the LV132 clone. Only three bands were detected using Northern blot analysis suggesting that the L-family could be derived from various mRNAs and from post-translational maturations. Southern analysis of genomic DNA suggests that the L-mRNAs were encoded by at least two distinct genes which could exist in numerous copies. The L-gene expression was studied under various physiological conditions and was found to be androgen-dependent. Furthermore, the results suggest the presence of a translational regulation in the newly differentiated epithelial cells.