The post‐translational modifications of Ral and Rac1 are important for the action of Ral‐binding protein 1, a putative effector protein of Ral

FEBS Letters

Koyama, Shinya¹  Hinoi, Takao¹  Matsubara, Kenji¹  Kikuchi, Akira¹ 

[1] Department of Biochemistry, Hiroshima University School of Medicine, 1-2-3 Kasumi, Minami-ku, Hiroshima 734, Japan

关键词: Ral;    RalBP1;    GAP;    Subcellular localization;    Rac1;    G protein;    GTP-binding protein;    RalGDS;    Ral GDP dissociation stimulator;    GAP;    GTPase-activating protein;    RalBP1;    Ral-binding protein 1;    PCR;    polymerase chain reaction;    MBP;    maltose-binding protein;    GST;    glutathione-S-transferase;    E. coli;    Escherichia coli;    HA;    hemagglutinin;    DTT;    dithiothreitol;    GTPγS;    guanosine 5′-(3-O-thio)triphosphate;    BSA;    bovine serum albumin;    CHAPS;    3-[(3-cholamidopropyl)dimetylammonio]-1-propanesulfonic acid;   

DOI  :  10.1016/S0014-5793(97)00633-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Ral-binding protein 1 (RalBP1) is a putative effector protein of Ral and possesses the GTPase-activating activity for Rac1 and CDC42. We examined the roles of the post-translational modifications of Ral and Rac1 for the action of RalBP1. In COS cells, Ral^G23V, a constitutively active form, was mainly detected in the membrane fraction while most of Ral^G23V/C203S, a Ral mutant which is not post-translationally modified, was found in the cytosol fraction. When RalBP1 was expressed alone in COS cells, it was found in the cytosol but not in the membrane fraction. When RalBP1 was coexpressed with Ral^G23V, a part of RalBP1 was found in the membrane fraction. However, when RalBP1 was coexpressed with Ral^G23V/C203S, all of RalBP1 was recovered in the cytosol fraction. Although Ral bound to RalBP1 at a molar ratio of 1:1, the interaction of Ral with RalBP1 did not affect the GTPase-activating activity of RalBP1 for Rac1. Furthermore, RalBP1 was more active on the post-translationally modified form of Rac1 and CDC42 than the unmodified form. These results suggest that the post-translational modification of Ral is important for the subcellular localization of RalBP1 and that the interaction of Ral with RalBP1 is not essential for the activity of RalBP1 but plays a role in recruiting RalBP1 to the membrane where its substrates, Rac1 and CDC42, reside.

【 授权许可】

Unknown