GENETIC-MAPPING AND EMBRYONIC EXPRESSION OF A NOVEL, MATERNALLY TRANSCRIBED GENE MEM3

To study the molecular function of genes expressed during preimplantat ion development, we isolated a novel maternal transcript SSEC (Stage S pecific Embryonic cDNA)-26 from a par tial subtraction library of mous e unfertilized eggs and preimplantation embryos. The SSEC-26 transcrip t is abundant in the unfertilized egg and also actively transcribed fr om the newly formed zygotic genome. On the basis of its expression in eggs and embryos, this new mouse gene is named Mem (maternal-embryonic ) 3. The genomic locus of Mem3 has been mapped to Chromosome (Chr) 8 n ear the D8Mit78 marker and the glutaryl CoA dehydrogenase (Gcdh) locus . The deduced amino acid sequence of MEM3 resembles that of the yeast VPS (Vacuolar Protein Sorting) 35 in two separate domains. A cDNA sequ ence of the potential human homolog of Mem3 has been assembled with pa rtial clones from the EST database and assigned to human Chr 16.