ISOLATION AND CHARACTERIZATION OF A CDNA-ENCODING THE ALPHA' SUBUNIT OF HUMAN CONE CGMP-PHOSPHODIESTERASE

A human cDNA (alpha'-PDE) encoding the alpha' catalytic subunit of con e photoreceptor cGMP-phosphodiesterase has been isolated and character ized. The nucleotide sequence of 2980 bp contains an open reading fram e encoding an 859-amino-acid (aa) protein with a calculated molecular mass of 99 kDa. Northern blot analysis of human retinal mRNA hybridize d with the alpha'-PDE cDNA revealed a signal corresponding to a 3.2-kb transcript. Comparison of the deduced aa sequence of human cone alpha '-PDE with corresponding proteins isolated from bovine and chicken ret inas shows 89 and 83% identity, respectively, and indicates that alpha '-PDE has been very well conserved in the evolutionary process. Human cone alpha'-PDE is highly homologous to rod alpha-PDE and beta-PDE, su ggesting that these proteins may have a close phylogenetic relationshi p.