The novel isoform of the progesterone receptor cDNA in the human testis and detection of its mRNA in the human uterine endometrium.

A novel isoform (termed isoform S) of the progesterone receptor (PR) cDNA (PR isoform S cDNA) which consists of a previously unidentified 5' sequence and exons 4-8 of the intracellular PR gene has been cloned from the human testicular cDNA library. The 5' sequence of the message was confirmed to be derived from a novel exon (termed exon S) by genomic cloning. The expression level of the PR isoform S mRNA was higher in the spermatozoon than in the uterine endometrium with a lower expression level of the PR isoforms B and A mRNAs in the spermatozoon than in the endometrium. These results implied that the PR isoform S which was possibly translated from the PR isoform S mRNA in the spermatozoon might be related to the cell surface membrane PR. Moreover, the PR isoform S in the uterine endometrium might play some physiological and/or pathogenic roles.