Immunogen sequence: IKTYSWDNAQ VILVGNKCDM EDERVISTER GQHLGEQLGF EFFETSAKDN INVKQTFERL VDIICDKMSE SLETDPAITA AKQNTRLKET PPPPQPNCAC. Rab proteins are low-molecular-weight GTP-binding proteins that form the largest branch of the Ras superfamily of GTPases.