Phosphorylation of a 62 kd porcine alpha-internexin, a newly identified intermediate filament protein.
A 62 kd protein was purified from the Triton-insoluble fraction of porcine brain white matter. This protein formed 10nm filaments, in vitro. The phosphorylation of the 62 kd protein by cAMP-dependent protein kinase caused electrophoretic mobility to shift to 66 kd on SDS-PAGE and a complete loss of the filament forming ability ensued. Amino acid sequences of four peptide fragments obtained from the 62 kd protein by lysylendopeptidase were identical with that of a 66 kd rat brain alpha-internexin. Amino acid analyses of the phosphopeptide fragment derived from phosphorylated porcine alpha-internexin revealed that the phosphorylation sites by cAMP-dependent protein kinase located in the amino-terminal head domain of this protein. These results strongly suggest that alpha-internexin polymerizes into 10nm filaments in vitro and that phosphorylation of the amino-terminal domain of alpha-internexin controls its polymerizability.
Tanaka
J
J
Department of Neurophysiology, Tokyo Metropolitan Institute of Gerontology, Japan.
Ogawara
M
M
Ando
S
S
Shibata
M
M
Yatani
R
R
Kusagawa
M
M
Inagaki
M
M
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000378:metabolism* / Q000648:ultrastructure; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D007382:Intermediate Filaments / Q000378:metabolism* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D010748:Phosphopeptides / Q000737:chemistry; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013552:Swine
D000596:Amino Acids; D002352:Carrier Proteins; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010748:Phosphopeptides; C046643:alpha-internexin; D011494:Protein Kinases