Isolation of the rat gene for Mullerian inhibiting substance.

Mullerian inhibiting substance (MIS), a testicular glycoprotein also known as anti-Mullerian hormone, plays a key role in male sexual development by causing regression of the Mullerian duct, the anlagen of the uterus, the Fallopian tubes, and part of the vagina. MIS is also expressed in the postnatal ovary, but its precise function is still not known. We report here the complete nucleotide sequence of the rat MIS gene. Rat MIS is encoded in five exons and is synthesized as a precursor of 553 amino acids, containing a 24-amino-acid leader. Based on homology with human MIS, we predict that the rat protein undergoes proteolytic processing at a site 108 amino acids from the C-terminus. Expression of the rat MIS mRNA is high in the 1-day-postnatal testis and decreases to a low level in the adult testis. In contrast, expression is not detected in the 1-day ovary, but increases to an intermediate level in the adult ovary. The rat gene should provide a good model for studying transcriptional regulation of MIS in the testis and ovary.