The S100B protein inhibits phosphorylation of GFAP and vimentin in a cytoskeletal fraction from immature rat hippocampus.
The S100B protein belongs to a family of small Ca2+-binding proteins involved in several functions including cytoskeletal reorganization. The effect of S 100B on protein phosphorylation was investigated in a cytoskeletal fraction prepared from immature rat hippocampus. An inhibitory effect of 5 microM S100B on total protein phosphorylation, ranging from 25% to 40%, was observed in the presence of Ca2+ alone, Ca2+ plus calmodulin or Ca2+ plus cAMP. Analysis by two dimensional electrophoresis revealed a Ca2+/calmodulin-dependent and a Ca2+/cAMP-dependent inhibitory effect of S100B, ranging from 62% to 67% of control, on the phosphorylation of the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. The fact that S100B binds to the N-terminal domain of GFAP and that the two proteins are co-localized in astrocytes suggests a potential in vivo role for S100B in modulating the phosphorylation of intermediate filament proteins in glia.
Ziegler
D R
DR
Departamento de Bioquímica, ICBS, UFRGS, Porto Alegre, Brazil.
Innocente
C E
CE
Leal
R B
RB
Rodnight
R
R
Gonçalves
C A
CA
D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D009414:Nerve Growth Factors / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D014746:Vimentin / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat; D014746:Vimentin