Molecular cloning of cDNAs and expression of mRNAs encoding α and β subunits of soluble guanylyl cyclase from medaka fish Oryzias latipes

Two cDNA clones encoding α and β subunits of soluble guanylyl cyclase (GC) were isolated from medaka fish ( Oryzias latipes ) cDNA libraries and designated as OlGCS‐α 1 and OlGCS‐β 1 , respectively. The ORF of OlGCS‐α 1 encodes 678 amino acids and that of OlGCS‐β 1 encodes 614 amino acids. Both subunits have a putative catalytic domain conserved with membrane GC and adenylyl cyclases. The amino acid sequences of OlGCS‐β 1 and mammalian soluble GC subunits are highly conserved throughout the entire protein, suggesting that amino acid sequences outside the catalytic domain are important for the functioning of the β subunit. On the contrary, amino acid sequences of α subunits outside the catalytic domain are fairly divergent between fish and mammals. Reverse transcription/PCR (RT/PCR) analysis showed that OlGCS‐α 1 and OlGCS‐β 1 transcripts were abundant in the brain, eye, spleen and testis. RT/PCR analysis demonstrated that both transcripts were present in unfertilized eggs, were reduced immediately after fertilization, then increased again. In addition, our results suggest that expression patterns of OlGCS‐α 1 and OlGCS‐β 1 genes are different from each other both during development and in adults.