Interaction of actin with the capping protein, CapZ from sea bass (Dicentrarchus labrax) white skeletal muscle.
We have compared the functional properties of CapZ from fish white skeletal muscle with those of CapZ from chicken muscle. CapZ is a heterodimer, which enhances actin nucleation and inhibits the depolymerization process by binding to the barbed ends of microfilaments. Here, we report the interaction of CapZ not only with F-actin, but also with monomeric actin. The affinity of sea bass CapZ for G-actin estimated by enzyme-linked immunosorbent assay (ELISA) was in the microM range. This association was PIP2 dependent. Binding contacts with the barbed end of actin were delimited by both ELISA and fluorescence approaches. One site (actin sequence 338-348) was located in a helical region of the subdomain 1, region already implicated in the interaction with other actin binding proteins such as gelsolin. Another site implicates the C-terminal region (sequence 360-372) of actin. Finally, the partial competition of antibodies directed against CapZ alpha or beta-subunits towards CapZ interaction with actin filaments suggests both subunits participate in the complex with actin.
UMR 5539 CNRS, Laboratoire de Recherche sur la Motilité Cellulaire EPHE, Université de Montpellier, France.
O
O
Kwiateck
I
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Papa
M C
MC
Lebart
Y
Y
Benyamin
C
C
Roustan
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001492:Bass / Q000378:metabolism*; D051347:CapZ Actin Capping Protein; D002645:Chickens; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D007074:Immunoglobulin G / Q000276:immunology; D008840:Microfilament Proteins / Q000378:metabolism*; D008970:Molecular Weight; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D011817:Rabbits
D000199:Actins; D051347:CapZ Actin Capping Protein; D007074:Immunoglobulin G; D008840:Microfilament Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D010716:Phosphatidylinositols