Rhodopsin-family receptors associate with small G proteins to activate phospholipase D

The activation of phospholipase D that is induced by many, but not all, Ca2+-mobilizing G-protein-coupled receptors is sensitive to inhibitors of ARF and RhoA. These receptors contain the amino-acid sequence AsnProXXTyr in their seventh transmembrane domain, while receptors able to activate phospholipase D without involving ARF contain the sequence AspProXXTyr. One functional result of the association between certain rhodopsin-family receptors and the small G proteins ARF and RhoA seems to be an increased coupling of receptors to phospholipase D activation.