F-actin capping by cap32/34 requires heterodimeric conformation and can be inhibited with PIP2.
The heterodimeric F-actin capping protein cap32/34 from Dictyostelium discoideum is a typical member of a widely distributed family of cytoskeletal proteins. To analyze its regulation and structure/function relationships we cloned and expressed the subunits separately in Escherichia coli using the ATG-expression vector pT7-7. Studies on the viscosity of F-actin solutions and the kinetics of actin polymerization in the presence of single subunits or the reconstituted protein showed that capping of F-actin absolutely requires the heterodimeric conformation. This activity can be inhibited by phosphatidyl bisphosphate (PIP2), an important component in signal transduction. The regulation of cap32/34 by PIP2 suggests an involvement of this protein in the re-organization of the actin cytoskeleton upon stimulation of D. discoideum cells with chemoattractant.
Haus
U
U
Max-Planck-Institute for Biochemistry, Martinsried, Federal Republic of Germany.
Hartmann
H
H
Trommler
P
P
Noegel
A A
AA
Schleicher
M
M
D000199:Actins / Q000378:metabolism*; D000818:Animals; D003001:Cloning, Molecular; D004023:Dictyostelium / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D007700:Kinetics; D046911:Macromolecular Substances; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000494:pharmacology*; D011487:Protein Conformation; D015800:Protozoan Proteins; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D014162:Transfection; D014783:Viscosity
D000199:Actins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C069272:cap32-34 protein, Dictyostelium