Volume 7, Issue 3, Pages 615-626 (March 2001) Phosphoprotein–Protein Interactions Revealed by the Crystal Structure of Kinase- Associated Phosphatase in Complex with PhosphoCDK2  Haiwei Song, Neil Hanlon, Nicholas R. Brown, Martin E.M. Noble, Louise N. Johnson, David Barford  Molecular Cell  Volume 7, Issue 3, Pages 615-626 (March 2001) DOI: 10.1016/S1097-2765(01)00208-8

Figure 1 Structures of KAP and PTP1B (A) Stereo view showing a 2Fo-Fc electron density omit map contoured at 1σ in the vicinity of the catalytic Cys residue (Cys-140) of wild-type KAP revealing the formation of a disulphide bond to Cys-79. (B) Ribbon diagram comparing KAPt with PTP1B. The PTP loop of both molecules is shown in yellow, the acid/base loop (WPD loop) in red, and the Q loop in white. The pTyr recognition segment of PTP1B is in green. A sulfate ion and pTyr residue are shown at the catalytic sites of KAPt and PTP1B, respectively. Figures were created using AESOP (M. E. M. N., unpublished data), BOBSCRIPT (Esnouf, 1997), and Raster3D (Merit and Murphy, 1994) Molecular Cell 2001 7, 615-626DOI: (10.1016/S1097-2765(01)00208-8)

Figure 2 Views of the pCDK2/KAPt Complex (A) Overview of the complex showing how the interaction between pCDK2 (yellow) and KAPt (cyan) positions the catalytic site of KAPt to face the activation segment of pCDK2. The activation segment of pCDK2 is in green and the PTP loop of KAP is dark blue. Residues 36–43 of pCDK2 are disordered and are not shown. (B) Stereo view showing the region of the activation segment with the pThr160 residue of pCDK2 bound to the catalytic site of KAPt. Ser-140 and Asp-110 are shown in close proximity to the phosphoamino acid. The WPD, PTP, and Q loops are in red, yellow, and white, respectively Molecular Cell 2001 7, 615-626DOI: (10.1016/S1097-2765(01)00208-8)

Figure 3 The pCDK2 αG/L14-KAP Interface (A) Details of the interactions involving the GDSEID motif (G helix) and DYK motif (L14) of CDK2 (gold) with the C-terminal helix of KAPt (cyan). (B) Comparison of the CDK2 surface area buried in the pCDK2/KAPt complex with the CDK2/CksHs1 interface. The common GDSEID interface surface is colored in gold, and the activation segment and β1-β2 hairpin interface of the pCDK2/KAPt complex are in green and white, respectively. The C helix is colored magenta. At the GDSEID interface, the surface area buried in the pCDK/KAPt and CDK2/CksHs1 complexes is 950 Å2 and 1313 Å2, respectively. The total surface buried by the GDSEID and the activation segment residues in the pCDK2/KAPt complex is 1866 Å2. To the right is a representation of pCDK2 with the molecular surface colored blue and green, representing those residues that interact uniquely with KAP (174, 205, and 236) and Cks1 (213 and 239–243), respectively, and red for residues interacting with both KAP and Cks1 (206–210, 235, and 237) Molecular Cell 2001 7, 615-626DOI: (10.1016/S1097-2765(01)00208-8)

Figure 4 The Conformation of pCDK2 in the pCDK2/KAPt Complex Represents the Activated Conformation A structural comparison of CDK2 as the nonphosphorylated monomer in the pCDK2/cyclin A complex and in the pCDK2/KAPt complex. Except for differences in the conformation of the activation segment residues 152–165, the conformation of CDK2 in the pCDK2/cyclin A binary complex is most similar to the pCDK2/KAPt structure. The N- and C-terminal lobes of CDK2 are colored white and gold, respectively, and the C helix is shown in magenta. The activation segment is green, except for residues 153–164 that are disordered in monomeric pCDK2 and are shown in red Molecular Cell 2001 7, 615-626DOI: (10.1016/S1097-2765(01)00208-8)

Figure 5 Model of a Putative pCDK2/Cyclin A/KAPt Ternary Complex The binding sites of cyclin A (magenta) and KAP on pCDK2 are nonoverlapping, allowing simultaneous interactions. The activation segment of pCDK2 is shown in red and green from the pCDK2/cyclin A and pCDK2/KAPt structures, respectively. The substrate peptide (gray) binding site on the kinase subunit and the RXL recruitment peptide (yellow) on cyclin A do not contact KAP, suggesting that KAP interactions with pCDK2/cyclin A would not interfere with kinase activity Molecular Cell 2001 7, 615-626DOI: (10.1016/S1097-2765(01)00208-8)