Identification of a C‐terminal binding site for G‐protein βγ‐subunits in phosducin‐like protein

FEBS Letters

Lohse, Martin J¹  Schröder, Stefan¹  Dees, Christian¹  Blüml, Klaus¹ 

[1] Institute of Pharmacology, University of Würzburg, Versbacher Straße 9, D-97078 Würzburg, Germany

关键词: Phosducin-like protein;    G-protein βγ-subunit;    β-Adrenergic receptor kinase;    Gα;    G-protein α-subunits;    Gβ;    G-protein β-subunits;    Gβγ;    G-protein βγ-subunits;    GST;    glutathione S-transferase;    PhLP;    phosducin-like protein (short variant);    βARK;    β-adrenergic receptor kinase-1;    Mas-7;    mastoparan analogue (Ile-Asn-Leu-Lys-Ala-Leu-Ala-Ala-Leu-Ala-Lys-Ala-Leu-Leu-NH2);   

DOI  :  10.1016/S0014-5793(96)01483-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Phosducin-like protein (PhLP) has recently been identified as a ubiquitous inhibitor of G-protein βγ-subunit (G_βγ)-mediated signaling, with an affinity about 5-fold lower than that of phosducin. The G_βγ binding site of phosducin has been suggested to be contained in its N-terminus. A region corresponding to this N-terminus is lacking in PhLP, suggesting that PhLP must utilize a different mode of G_βγ binding. To map the G_βγ binding site in PhLP, a series of deletion mutants were constructed, expressed in E. coli as glutathione S-transferase (GST) fusion proteins, and the purified fusion proteins were examined for their ability to attenuate G_o GTPase activity. Progressive N-terminal truncations of PhLP caused only minor reductions in potency, whereas the complementary N-terminal PhLP fragments turned out to be inactive. We further identified a short C-terminal segment comprising residues 168 to 195 that inhibited G_o GTPase activity similar in efficacy and potency to full-length PhLP. This C-terminal fragment was also capable of antagonizing a second G_βγ-mediated function, the enhancement of rhodopsin phosphorylation by the β-adrenergic receptor kinase. Taken together, these data indicate that PhLP interacts with G_βγ via a short C-terminal binding site which is distinct from that identified previously in phosducin.

【 授权许可】

Unknown