Four independent phage clones containing the fragments of cone-specific cGMP phosphodiesterase (PDE) α′ subunit (PDEα′) cDNA were isolated from the human cDNA library. The screening of the genomic library resulted in isolation of four independent phage clones with the fragments of human cone PDEα′ gene including 5′-flanling region and exons ranged from 1 to 14 (overall 32 kilobases). Structural studies of the clones made it possible to establish the complete human cone PDEα′ cDNA structure (3455 base pairs). The encoding polypeptide consists of 858 amino acid residues with a calculated molecular mass of 99169 Da. The deduced amino acid sequence displays high homology to the earlier analyzed catalytic α, β and α′ subunits of bovine, human, chicken and mouse photoreceptor PDEs.
