{Reference Type}: Journal Article {Title}: Solution structure and backbone dynamics of human Raf-1 kinase inhibitor protein. {Author}: Guo C;Yi C;Peng Y;Wen Y;Lin D; {Journal}: Biochem Biophys Res Commun {Volume}: 438 {Issue}: 1 {Year}: Aug 2013 16 {Factor}: 3.322 {DOI}: 10.1016/j.bbrc.2013.07.039 {Abstract}: Human Raf-1 kinase inhibitor protein (hRKIP) is a small multi-functional protein of 187 residues. It contains a conserved pocket, which binds a wide range of ligands from various small molecules to distinct proteins. To provide a structural basis for the ligand diversity of RKIP, we herein determined the solution structure of hRKIP, and analyzed its structural dynamics. In solution, hRKIP mainly comprises two antiparallel β sheets, two α helices and two 3₁₀ helices. NMR dynamic analysis reveals that the overall structure of hRKIP is rigid, but its C-terminal helix which is close to the ligand-binding site is mobile. In addition, residues around the ligand-binding pocket exhibit significant conformational exchange on the μs-ms timescale. Conformational flexibility may allow the ligand-binding pocket and the C-terminal helix to adopt various conformations to interact with different substrates. This work may shed light on the underlying molecular mechanisms of how hRKIP recognizes and binds diverse substrate ligands.