Characterization of Additional Casein Kinase I Sites in the C-Terminal "Tail" Region of Chicken and Rat Neurofilament-M |
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Authors: | Gerry Shaw,Rehae Miller,Deng-Shun Wang,Dali Tang, Brian A. Hollander, &dagger Gudrun S. Bennett |
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Affiliation: | Department of Neuroscience and Brain Institute and; Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida, U.S.A. |
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Abstract: | Abstract: In previous studies we have identified Ser502, Ser528, and Ser534 as target sites in chicken neurofilament middle molecular mass protein (NF-M) for casein kinase I (CKI) in vitro and have shown that these sites are also phosphorylated in vivo. We now make use of a combination of molecular biological and protein chemical techniques to show that two additional in vivo phosphorylation sites in chicken NF-M, Ser464 and Ser471, can also be phosphorylated by CKI in vitro. These two sites are conserved in higher vertebrate NF-M molecules, and recombinant protein constructs containing the homologous rat NF-M peptides can be phosphorylated by CKI in vitro, suggesting that phosphorylation of these sites is conserved at least in higher vertebrates. The two new sites are adjacent to a conserved peptide sequence (VEE-IIEET-V) found once in higher vertebrate NF-M molecules and twice in lamprey NF-180. Variants of this sequence are also found in neurofilament low and high molecular mass proteins (NF-L and NF-H) and α-internexin, and in mammalian NF-L are known to be associated with in vivo phosphorylation sites. We speculate that CKI phosphorylation in general, and these sites in particular, may be important in neurofilament function. |
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Keywords: | Neurofilament-M Neurofilament kinase Casein kinase I Phosphorylation sites Cytoskeleton |
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