Characterization of a neurofilament-associated kinase that phosphorylates the middle molecular mass component of chicken neurofilaments.
We have examined the properties of a chicken neurofilament (NF) kinase partially purified from NF-enriched preparations. This kinase cosediments with NFs following extraction with Triton X-100 and can be separated in an active form from NFs by treatment with 0.8 M KCl. Sequential chromatography of the salt extract on DEAE-cellulose and phosphocellulose results in an approximately 500-fold increase in specific activity over endogenous NF preparations as measured by 32P-incorporation into the middle molecular mass component of NFs (NF-M). The kinase is Mg(2+)-dependent, second messenger-independent and inhibited by high concentrations of heparin. It shows selectivity for NF-M and evidence is presented that the kinase phosphorylates NF-M solely in the tail domain. The kinase can also phosphorylate the microtubule-associated proteins tau and MAP2 as well as mammalian NF-M, all of which share putative phosphorylation sequences with chicken NF-M.
Hollander
B A
BA
Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville 32610.
Bennett
G S
GS
D000818:Animals; D002645:Chickens; D007382:Intermediate Filaments / Q000201:enzymology*; D008970:Molecular Weight; D016900:Neurofilament Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis* / Q000378:metabolism; D013379:Substrate Specificity
D016900:Neurofilament Proteins; D011494:Protein Kinases