Expression and characterization of human PDEdelta and its Caenorhabditis elegans ortholog CEdelta.

Cyclic GMP phosphodiesterase (PDE) is rod photoreceptor disk membrane-associated via C-terminal lipid tails. PDEdelta, a recently identified subunit, was shown to disrupt PDE/membrane interaction under physiological conditions, without affecting PDE catalytic activity. We found that a PDEdelta ortholog from the eyeless nematode Caenorhabditis elegans (termed CEdelta) solubilizes bovine PDE in vitro with an EC50 very similar to PDEdelta. Immobilized PDEdelta and CEdelta both bind, in addition to bovine PDE, an N-terminal fragment of human retinitis pigmentosa GTPase regulator, but not rhodopsin kinase and Ran binding protein 1. The results suggest that PDEdelta and CEdelta may regulate membrane binding of a variety of proteins in photoreceptors and other tissues.