Preferential Binding Of cGMP Phosphodiesterase To Phospholipid Monolayers

Abstract

The light-activated rhodopsin, metarhodopsin II, forms a complex with the alpha subunit of transducin (Tα). The exchange of GDP for GTP leads to a conformational change of Tα which is released from its beta-gamma subunits and rhodopsin. Tα-GTP then activates cGMP phosphodiesterase (PDE) which hydrolyzes cGMP and leads to the closure of the cGMP-gated channels and to the hyperpolarization of the rod photoreceptors. PDE is made of two catalytic (αβ) and two inhibitory (γ) subunits (Pαβγγ). PDE is acylated with a farnesyl and a geranylgeranyl and is thus membrane bound.