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Dephosphorylated but not phosphorylated microtubule associated protein MAP1B binds to microfilaments
Author(s) -
Pedrotti Barbara,
Islam Khalid
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00520-0
Subject(s) - microfilament , dephosphorylation , phosphorylation , casein kinase 2 , actin , phosphatase , microtubule , cytoskeleton , kinase , microbiology and biotechnology , chemistry , protein kinase a , biochemistry , biology , cell , cyclin dependent kinase 2
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.