EXPRESSION AND STRUCTURAL-ANALYSIS OF A TELEOST HOMOLOG OF A MAMMALIAN ZONA-PELLUCIDA GENE

Gene expression in oviparous vertebrates during vitellogenesis is horm onally regulated. Our laboratory has characterized a unique gene (wf f emale), which is seasonally expressed in the liver of the female winte r flounder Pseudopleuronectes americanus. The wf female mRNA is coexpr essed with vitellogenin mRNA and reaches a high level during vitelloge nesis. The wf female gene is 2554 base pairs in length and encodes a p utative protein of 509 amino acids. The gene consists of eight exons s eparated by seven introns of different sizes. Within exon 1, there are six PQQ-rich repeats. Four of them encode a putative (PQQ)4PKY polype ptide, similar to the repeats found in the extracellular domains of ot her proteins. Exons 2-7 share homology with the zona pellucida protein genes rc55 of rabbit and zp-2 of mouse, and the positions of intron b oundaries are conserved in the wf female and mouse zp-2 genes. In addi tion, the transcriptional regulatory cis elements (estrogen response e lement, CCAAT and TATAAA boxes), as found in vertebrate genes, are als o conserved for the wf female promoter and mapped upstream from the in itiation site of the wf female primary transcript.