Genomic structure and expression of the Medaka fish homolog of the mammalian guanylyl cyclase B

We have isolated a 3.9-kbp-long cDNA and approximately 93 kbp long genomic DNA encoding a membrane guanylyl cyclase (designated OlGC1) from the medaka fish Oryzias latipes, and determined their nucleotide sequences. The open reading frame for the OlGC1 cDNA predicts a protein of 1,055 amino acids. Phylogenetic analysis indicates OlGC1 to be a medaka fish homolog of mammalian guanylyl cyclase B (GC-B), a member of the natriuretic peptide receptor family. Northern blot analysis demonstrated 3.9 kb OlGC1 transcripts in the eye and brain, while reverse transcription-polymerase chain reaction (RT-PCR) analysis showed OlGC1 transcripts in a number of adult peripheral organs as well as embryos during early stages of development. The OlGC1 gene consists of 22 exons with an exon/intron organization similar to that of the human and rat GC-A genes, except that OlGC1 has several very large introns, The OlGC1 gene has no apparent TATA box or CAAT box in the region 1.2 kbp upstream of the putative transcription initiation point, but several consensus sequences for cis-regulatory elements, including an NF-IL6-binding element, a shear stress responsive element, and multiple GM-CSF-binding elements, are present in that region.