Biochemical and functional analysis of highly phosphorylated forms of c‐Jun protein

FEBS Letters

Takada, Mizuho¹  Ito, Taiji¹  Ui, Motoyasu¹  Murakami, Masao¹  Sonobe, Martha H.¹  Sato, Toshitaka²  Iba, Hideo¹  Okazaki, Satoshi¹ 

[1] Department of Gene Regulation, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan;Tsukuba Research Laboratories, Eisai Co., Ltd. 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan

关键词: c-Jun;    c-Jun N-terminal kinase;    Phosphorylation;    Cellular transformation;    Ultraviolet irradiation;    JNK;    c-Jun N-terminal kinase;    MAPK;    mitogen-activated protein kinase;    CIP;    calf intestine alkaline phosphatase;    CEF;    chicken embryo fibroblasts;   

DOI  :  10.1016/S0014-5793(98)00618-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We report here that, upon UV irradiation or growth stimulation, endogenous c-Jun (40 kDa) in chicken embryo fibroblasts (CEF) is converted into several forms with apparently higher molecular weights in SDS-polyacrylamide gel electrophoresis (45, 44, 42 kDa). Two of the bands (44 and 45 kDa) were transient after growth stimulation, but were much more persistent after UV irradiation. In both cases, the drastic mobility shifts were accompanied with the activation of endogenous JNK activity but not of MAPK activity, and the bands were shown to represent different phosphorylation states of c-Jun rather than ubiquitinated c-Jun. Biochemical analysis indicated that phosphorylation at Ser⁶³ and Ser⁷³ was not sufficient to produce these drastic mobility shifts, which additionally required phosphorylation at Thr⁹¹ and Thr⁹³. Substitution of both Ser⁶³ and Ser⁷³ with either Ala or Asp had no significant effect on the transforming activity of c-Jun, but the mutants failed to show drastic mobility shifts even after UV irradiation. These results indicate that Ser⁶³ and Ser⁷³ are essential for the drastic mobility shifts and further suggest that the highly phosphorylated forms of c-Jun are not directly involved in cellular transformation.

【 授权许可】

Unknown