Identification and characterization of an actin-binding site of CapZ.
A mAb (1E5) that binds the COOH-terminal region of the beta subunit of chicken CapZ inhibits the ability of CapZ to bind the barbed ends of actin filaments and nucleate actin polymerization. CapZ prepared as fusion proteins in bacteria or nonfusion proteins by in vitro translation has activity similar to that of CapZ purified from muscle. Deletion of the COOH-terminus of the beta subunit of CapZ leads to a loss of CapZ's ability to bind the barbed ends of actin filaments. A peptide corresponding to the COOH-terminal region of CapZ beta, expressed as a fusion protein, binds actin monomers. The mAb 1E5 also inhibits the binding of this peptide to actin. These results suggest that the COOH-terminal region of the beta subunit of CapZ is an actin-binding site. The primary structure of this region is not similar to that of potential actin-binding sites identified in other proteins. In addition, the primary structure of this region is not conserved across species.
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri.
C
C
Hug
T M
TM
Miller
M A
MA
Torres
J F
JF
Casella
J A
JA
Cooper
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D001665:Binding Sites; D051347:CapZ Actin Capping Protein; D002645:Chickens; D000939:Epitopes; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D000199:Actins; D000911:Antibodies, Monoclonal; D051347:CapZ Actin Capping Protein; D000939:Epitopes; D008840:Microfilament Proteins; D009124:Muscle Proteins; D011993:Recombinant Fusion Proteins