Structure and expression of Furin mRNA in the ovary of the medaka, Oryzias latipes

A cDNA for furin was cloned from the ovary of the medaka, Oryzias latipes, by a combination of cDNA library screening, 5'-rapid amplification of cDNA ends (RACE), and 3'- RACE. The cDNA sequence codes for a protein of 814 amino acid residues highly homologous to other vertebrate furins, Ca(2+)-dependent serine proteases belonging to the subtilysin-like proprotein convertase family. The medaka preprofurin consists of a leader sequence, a propeptide with autoactivation sites, a Kex2-like catalytic domain, a P domain, a cysteine-rich domain, a putative transmembrane domain, and a cytoplasmic domain. The catalytic triad residues (Asp-164, His-205, and Ser-379) were all conserved. Furin mRNA was expressed in many tissues of this, including the ovary. In the ovary, the greatest expression of furin mRNA occurred in oocytes of small growing follicles, as demonstrated by Northern blotting, RT-PCR, and in situ hybridization analysis. Temporary and spatial expression patterns of the medaka fish furin were similar to those of stromelysin-3 and MT5-MMP during oocyte growth and postnatal development.