Ras Like Without CAAX 1 (RIT1)

Human and mouse RIT have 5 highly conserved domains characteristic of small G proteins, but they lack the C-terminal CAAX prenylation motif found in several other RAS-like proteins. Northern blot analysis detected a 1.2-kb transcript in all mouse tissues examined. Epitope-tagged mouse Rit localized to the plasma membrane of transfected cells.Conversion of gln79 to leu in RIT resulted in complete loss of GTPase activity. The activity of RIT and RIN was significantly different from that of the majority of RAS-related GTPases, and the GTP dissociation rates were 5- to 10-fold faster than most RAS-like GTPases. Yeast 2-hybrid analysis showed that RIT and RIN interacted with the RAS-binding proteins RALGDS, RLF, and AF6 (MLLT4), but not with RAF kinases, RIN1, or the p110 subunit of PI3K.