Molecular plasticity of beta-catenin: new insights from single-molecule measurements and MD simulation.

The multifunctional protein, beta-catenin, has essential roles in cell adhesion and, through the Wnt signaling pathway, in controlling cell differentiation, development, and generation of cancer. Could distinct molecular forms of beta-catenin underlie these two functions? Our single-molecule force spectroscopy of armadillo beta-catenin, with molecular dynamics (MD) simulation, suggests a model in which the cell generates various forms of beta-catenin, in equilibrium. We find beta-catenin and the transcriptional factor Tcf4 form two complexes with different affinities.

Structure of a circularly permuted phosphoglycerate kinase.

The crystallographic structure of a circularly permuted form of yeast PGK, 72p yPGK, has been determined to a resolution of 2.3 A by molecular replacement. In this engineered protein, the C- and N-terminal residues of the wild-type protein are directly connected by a peptide bond and new N- and C-terminal residues are located within the N-terminal domain.