Phosphorylation modulates calpain-mediated proteolysis and calmodulin binding of the 200-kDa and 160-kDa neurofilament proteins.
The effects of enzymatic dephosphorylation on neurofilament interaction with two calcium-binding proteins, calpain and calmodulin, were examined. Dephosphorylation increased the rate and extent of 200-kDa neurofilament protein proteolysis by calpain. In contrast, dephosphorylation of the 160-kDa neurofilament protein did not alter the rate or extent of calpain proteolysis. However, the calpain-induced breakdown products of native and dephosphorylated 160-kDa neurofilament protein were different. Dephosphorylation did not change the proteolytic rate, extent, or breakdown products of the 68-kDa neurofilament protein. Calmodulin binding to the purified individual 160- and 200-kDa neurofilament proteins was increased following dephosphorylation. These results suggest that phosphorylation may regulate the metabolism and function of neurofilaments by modulating interactions with the calcium-activated proteins calpain and calmodulin.
Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham 35294-0017.
J A
JA
Greenwood
J C
JC
Troncoso
A C
AC
Costello
G V
GV
Johnson
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002154:Calpain / Q000494:pharmacology*; D008970:Molecular Weight; D016900:Neurofilament Proteins / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D010766:Phosphorylation
D002147:Calmodulin; D016900:Neurofilament Proteins; C051774:neurofilament protein H; C061195:neurofilament protein M; D010447:Peptide Hydrolases; D002154:Calpain