Rit

Rit and its neuron-specific homologue, Rin, define a recently discovered subfamily of Ras-related GTPases. Rit and Rin are membrane-associated in spite of the fact that they lack a CAAX box or similar C-terminal lipidation motif. Rit and Rin display 64% amino acid sequence identity and share a unique nine amino acid effector domain (DPTIEDAYK) that is 100% conserved between the murine and human proteins. Although the effector domain sequences of Rit and Rin are very similar to that of Ras, Rit and Rin have been shown to interact with the known Ras-binding proteins RalGDS, Rlf and AF-6, but not the Raf kinases, RIN1 or the p110 subunit of PI3 kinase. For this reason, it has been suggested that Rit and Rin may play important roles in the regulation of signaling pathways distinct from those controlled by Ras.