Phosphodiesterase 6G, cGMP Specific (PDE6G)

Cyclic GMP-phosphodiesterase plays a key role in the normal functioning of retinal rod photoreceptor cells. PDE6G is composed of alpha- and beta-catalytic subunits which are inhibited by 2 identical gamma subunits. The 1,012-bp cDNA had a coding region of 261 bp that was highly homologous to those of the corresponding cDNA from bovine and mouse retinas. Comparison of the deduced amino acid sequences from 3 species indicated evolutionary conservation. The cDNA encodes a 1.0-kb mRNA. Heterotrimeric guanosine 5-prime-triphosphate (GTP)-binding proteins (G proteins) are deactivated by hydrolysis of the GTP that they bind when activated by transmembrane receptors. Transducin, the G protein that relays visual excitation from rhodopsin to the phosphodiesterase in retinal photoreceptors, must be deactivated for the light response to recover.