Rhophilin-2 is targeted to late-endosomal structures of the vesicular machinery in the presence of activated RhoB.

Rhophilin-2 or p76(RBE), a protein whose expression is induced by the cyclic AMP pathway in thyrocytes, contains several protein-protein interaction domains including HR-1, Bro1 and PDZ domains, and is a partner of RhoB in its GTP-bound form (Eur J Biochem, 269(24): 6241-9, 2002). We here define its subcellular localization and dissect the significance of its domains. By subcellular fractionation and colocalization experiments, rhophilin-2 is recruited to subcellular organelles by activated RhoB-GTP.

Identification and characterization of a novel activated RhoB binding protein containing a PDZ domain whose expression is specifically modulated in thyroid cells by cAMP.

In a search for genes regulated in response to cAMP we have identified a new protein, p76RBE, whose mRNA and protein expression is enhanced in thyrocytes following thyrotropin stimulation of the cAMP transduction cascade. This protein presents important similarities with Rhophilin and contains different protein-protein interaction motifs. The presence of HR1 and PDZ motifs as well as a potential PDZ binding domain motif suggests that p76RBE could be implicated in targeting or scaffolding processes.