Homodimerization through coiled‐coil regions enhances activity of the myotonic dystrophy protein kinase

FEBS Letters

Zhang, Rongxin¹  Epstein, Henry F.¹ 

[1] Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA

关键词: Myotonic dystrophy;    Protein kinase;    Dimer;    Coiled-coil;    Activity;    DMPK;    myotonic dystrophy protein kinase;    FLAG peptide;    DYKDDDDK;    H;    α-helical region;    HA;    hemagglutinin antigen;    L;    leucine-rich region;    MDFPK;    myotonic dystrophy family of protein kinases;    MYPT1;    myosin binding subunit of myosin phosphatase;    PK;    protein kinase catalytic domain region;    SDGS;    sucrose density gradient sedimentation;    T;    transmembrane region;   

DOI  :  10.1016/S0014-5793(03)00601-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Myotonic dystrophy protein kinase (DMPK) is the protein product of the human DM-1 locus on chromosome 19q13.1 and has been implicated in the cardiac and behavioral dysfunctions of the disorder. DMPK contains four distinct regions: a leucine-rich repeat (L), a serine-threonine protein kinase catalytic domain (PK), an α-helical coiled-coil region (H), and a putative transmembrane-spanning tail (T). Multiple protein kinases that participate in cytoskeletal and cell cycle functions share homology with DMPK in the PK and H regions. Here we show that the LPKH and PKH subfragments of DMPK formed dimers of 140 000 molecular weight, whereas the LPK subfragment remained a monomer of 62 000 apparent molecular weight. The H domain thus appeared to be required for dimerization of DMPK subfragments. Caspase 1 cleaved LPKH between the PK and H regions. After cleavage, LPKH dimers became LPK-like monomers, consistent with the H domain mediating dimerization. The V _max and k _cat/K _m of LPKH with a synthetic peptide kinase substrate were over 10-fold greater than either LPK or caspase-cleaved LPKH. The K _m of dimeric LPKH was over three-fold greater than those of the monomeric proteins. Dimerization appeared to significantly affect the catalytic efficiency and substrate binding of DMPK. These interactions are likely to be functionally significant in other members of the myotonic dystrophy family of protein kinases with extensive coiled-coil domains.

【 授权许可】

Unknown