Dephosphorylated but not phosphorylated microtubule associated protein MAP1B binds to microfilaments

FEBS Letters

Pedrotti, Barbara²  Islam, Khalid¹ 

[1] Lepetit Research Center, Marion Merrell Dow Research Institute, 21040 Gerenzano (VA, Italy;Department of Biology, Cell Biology Laboratory, Università di Milano, Via Celoria 26, 20133 Milano, Italy

关键词: High-molecular weight MAPs;    MAP1B;    Phosphorylation;    Microfilaments;    Cytoskeleton;    EGTA;    ethylene glycol bis (β-aminoethyl ether)-N;    N;    N′;    N′;    -tetraacetic acid;    ATP;    adenosine 5′-triphosphate;    MAPs;    microtubule-associated proteins;    MES;    2-(N-morpholino) ethanesulphonic acid;    Tris;    Trizma base;    PAGE;    polyacrylamide gel electrophoresis;    SDS;    sodium dodecyl sulphate;    PMSF;    phenylmetane sulphonyl fluoride;    CKII;    casein kinase II;    PDPK;    proline-directed protein kinase;    AP;    alkaline phosphatase;   

DOI  :  10.1016/0014-5793(96)00520-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have reported that purified native MAP1B interacts with microtubules but not with microfilaments [Pedrotti and Islam, Cell Motil. Cytoskel. (1995) 30, 301–309]. However, MAP1B can be phosphorylated at multiple sites by casein kinase II (CKII) and proline-directed protein kinases (PDPK) and immunoblotting studies show that purified native MAP1B is phosphorylated at least at two CKII sites and at one PDPK site [Pedrotti et al., Biochemistry (1996) 35, 3016–3023]. We now show that phosphorylation affects the in vitro binding of MAP1B with microfilaments. Native MAP1B does not bind to microfilaments but after treatment with alkaline phosphatase the dephosphorylated MAP1B binds and cosediments with microfilaments. Dephosphorylation kinetics suggest that the PDPK site, but not CKII sites, may negatively regulate the interaction with F-actin. The ability of dephosphorylated MAP1B to crosslink microfilaments was also examined and showed that MAP1B exhibits only a weak crosslinking of F-actin when compared with MAP2.

【 授权许可】

Unknown