Ocat, a paternally expressed gene closely linked and transcribed in the opposite direction to Peg3

Two reciprocally imprinted Kruppel-type zinc finger genes, Peg3 and Zim1, h ave been found in close proximity on mouse proximal chromosome 7. Here, we describe the identification of another novel imprinted transcript, Ocat (os sification center-associated transcript). Ocat encodes a 5.5-kb spliced tra nscript and is transcribed in the opposite orientation to Peg3. One of its exons (putative exon 1) lies approximately 200 bp upstream of Peg3. Ocat is predominantly expressed in embryos from days 11 to 17, particularly in oss ification centers of the embryonic skeleton at day 15. Like Peg3, Ocat is e xpressed exclusively from the paternal allele. Despite their proximity, Peg 3 and Ocat showed dissimilar expression profiles, suggesting that they are regulated by independent genetic elements. (C) 2000 Academic Press.