CDNA CLONING OF A NOVEL RAINBOW-TROUT SRY-TYPE HMG BOX PROTEIN, RTSOX23, AND ITS FUNCTIONAL-ANALYSIS

We have isolated a cDNA clone for a new member of Sox genes, termed rt Sox23, from a rainbow trout ovary cDNA library. rtSox23 mRNA was notab ly expressed in ovary and brain. rtSox23 contains a leucine zipper in addition to an SRY-type HMG box. Although the recombinant HMG box regi on protein of rtSox23 could bind to an AACAAT sequence, the full-lengt h rtSox23 could form a homodimer and did not bind to the sequence. Fur thermore, using a two-hybrid system, we have isolated a cDNA clone enc oding a protein that bound to the leucine zipper region of rtSox23. Th is protein was the rainbow trout homologue of mouse nucleoporin p62, w hich is a component of the nuclear pore complex in nuclear envelope. T he rainbow trout p62 mRNA was also prominent in ovary and brain. Taken together, these results suggest that the rainbow trout p62 associates with rtSox23 in vivo and modulates the function of rtSox23. (C) 1998 Elsevier Science B.V.