Ras-associating domain proteins: A new class of cyclic nucleotide-gated channel modulators

Abstract

The Ras is a protein subfamily of small GTPases that are involved in cellular signal transduction. Members of Ras family are all related in structure and regulate diverse cell behaviors. Ras-associating/binding (RA/RBD) domain-containing proteins perform several different functions ranging from tumor suppression to being oncoproteins. Their role in different biological processes may be unclear and highly divergent but what is clear is that they convergently function by interacting with Ras proteins through their RA/RBD subdomains directly or indirectly. Apart from interacting with Ras proteins, there is no perceptible relationship between these proteins or their highly unrelated protein bodies. The heterogeneity among these RA domains allows them to interact with Ras proteins of different types as well as several other proteins which contain similar motifs. Very recently, we have demonstrated that growth factor receptor bound protein 14 (Grb14) RA domain binds to photoreceptor cyclic nucleotide-gated channel (CNG) and inhibits its activity in vivo. In this study, we have examined two other RA domain-containing protein phosphates expressed in retina, PHLPP1, and PHLPP2 on CNG channel activity. Our data indicate that not all RA domain proteins are modulators of CNG channel, suggesting the existence of heterogeneity among several RA domain proteins. © 2012 Springer Science+Business Media, LLC.