PDBsum entry: 1cnu

Contractile

PDB id: 1cnu

Contents

Protein chain

134 a.a. *

Waters ×114

* Residue conservation analysis

PDB id:

1cnu

Name:

Contractile

Title:

Phosphorylated actophorin from acantamoeba polyphaga

Structure:

Actophorin. Chain: a. Synonym: adf, cofilin. Engineered: yes. Other_details: phosphorylated on ser-1 (sep)

Source:

Acanthamoeba polyphaga. Organism_taxid: 5757. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.25Å R-factor: 0.204 R-free: 0.304

Authors:

L.Blanchoin,R.C.Robinson,S.Choe,T.D.Pollard

Key ref:

L.Blanchoin and T.D.Pollard (1998). Interaction of actin monomers with Acanthamoeba actophorin (ADF/cofilin) and profilin. J Biol Chem, 273, 25106-25111. PubMed id: 9737968 DOI: 10.1074/jbc.273.39.25106

Date:

24-May-99 Release date: 01-Jun-99

Protein chain

P37167  (ACTP_ACACA) -  Actophorin

Seq: 138 a.a.

Struc: 134 a.a.

 Gene Ontology (GO) functional annotation 

• Cellular component: intracellular (2 terms)
• Biochemical function: actin binding (1 term)

DOI no: 10.1074/jbc.273.39.25106

J Biol Chem 273:25106-25111 (1998)

PubMed id: 9737968

Interaction of actin monomers with Acanthamoeba actophorin (ADF/cofilin) and profilin.

L.Blanchoin, T.D.Pollard.

ABSTRACT

Acanthamoeba actophorin is a member of ADF/cofilin family that binds both actin monomers and filaments. We used fluorescence anisotropy to study the interaction of actin monomers with recombinant actophorin labeled with rhodamine on a cysteine substituted for Serine-88. Labeled actophorin retains its affinity for actin and ability to reduce the low shear viscosity of actin filaments. At physiological ionic strength, actophorin binds Mg-ADP-actin monomers (Kd = 0.1 microM) 40 times stronger than Mg-ATP-actin monomers. When bound to actin monomers, actophorin has no effect on elongation at either end of actin filaments by Mg-ATP-actin and slightly increases the rate of elongation at both ends by Mg-ADP-actin. Thus actophorin does not sequester actin monomers. Sedimentation equilibrium ultracentrifugation shows that actophorin and profilin compete for binding actin monomers. Actophorin and profilin have opposite effects on the rate of exchange of nucleotide bound to actin monomers. Despite the high affinity of actophorin for ADP-actin, physiological concentrations of profilin overcome the inhibition of ADP exchange by actophorin. Profilin rapidly recycles ADP-actin back to the profilin-ATP-actin pool ready for elongation of actin filaments.

Selected figure(s)

Figure 1.
Fig. 1. Ribbon diagram of Acanthamoeba actophorin based on the crystal structure of Leonard et al. (26). Residues Asn-33 (N33), Glu-70 (E70), and Ser-88 (S88), shown with ball and stick side chains, were replaced individually with cysteine to allow specific labeling of Acanthamoeba actophorin.

Figure 5.
Fig. 5. Competition between actophorin and profilin for binding actin monomers. Sedimentation equilibrium analytical centrifugation at 20,000 rpm at 25 °C in an AnTi rotor. Absorbance at 550 nM across five cells containing 5 µM actophorin alone ( ), 5 µM actophorin with 10 µM actin ( ), 5 µM actophorin with 10 µM actin, and 30 µM profilin ( circle ), 40 µM profilin ( ), or 50 µM profilin ( ). Solid and dashed lines correspond at the theoretical curves for single species with molecular weights of 14,000 and 66,000, respectively.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (1998, 273, 25106-25111) copyright 1998.

Figures were selected by an automated process.