RalA Binding Protein 1 (RALBP1)

Small G proteins have GDP-bound inactive and GTP-bound active forms; RAL proteins shift from the inactive to the active state through the actions of RALGDS. RALGDS interacts with the active form of RAS.

The deduced 655-amino acid protein is homologous in the central region to proteins bearing a CDC42 /RHO /RAC GTPase-activating protein (GAP) activity, such as BCR. Sequence analysis predicted that RALBP1 has an N-terminal alpha-helical region, the GAP-like region, the RAL-binding region, and the C-terminal region. Binding analysis showed that RALBP1 interacts with RALA and RALB but with no other GTPase except RAC1. Northern blot analysis detected ubiquitous, low-level expression of RALBP1.