PDBsum entry 1rpy

Signaling protein

PDB id: 1rpy

Contents

Protein chains

82 a.a. *

86 a.a. *

Ligands

SO4 ×2

Waters ×30

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Structural basis for recruitment of the adaptor protein aps to the activated insulin receptor.

Authors

J.Hu, J.Liu, R.Ghirlando, A.R.Saltiel, S.R.Hubbard.

Ref.

Mol Cell, 2003, 12, 1379-1389. [DOI no: 10.1016/S1097-2765(03)00487-8]

PubMed id

14690593

Abstract

The adaptor protein APS is a substrate of the insulin receptor and couples receptor activation with phosphorylation of Cbl to facilitate glucose uptake. The interaction with the activated insulin receptor is mediated by the Src homology 2 (SH2) domain of APS. Here, we present the crystal structure of the APS SH2 domain in complex with the phosphorylated tyrosine kinase domain of the insulin receptor. The structure reveals a novel dimeric configuration of the APS SH2 domain, wherein the C-terminal half of each protomer is structurally divergent from conventional, monomeric SH2 domains. The APS SH2 dimer engages two kinase molecules, with pTyr-1158 of the kinase activation loop bound in the canonical phosphotyrosine binding pocket of the SH2 domain and a second phosphotyrosine, pTyr-1162, coordinated by two lysine residues in beta strand D. This structure provides a molecular visualization of one of the initial downstream recruitment events following insulin activation of its dimeric receptor.

Figure 2.
Figure 2. Crystal Structure of the APS(SH2)-IRK ComplexRibbon diagram (top) and all-atom representation (bottom) of the APS(SH2)-IRK structure. The noncrystallographic 2-fold axis is vertical. The two IRK molecules are colored cyan, except for the activation loop, which is colored yellow. The two APS(SH2) protomers are colored green and purple. The three phosphotyrosine residues in the IRK activation loop are shown in ball-and-stick representation, with carbon atoms colored yellow, oxygen atoms colored red, and phosphorus atoms colored black. The bisubstrate inhibitor is colored orange, with the peptide portion shown in ribbon/coil representation, and the substrate tyrosine, linker, and ATPγS atoms shown in ball-and-stick representation. The N termini of the IRK molecules, which lead into the juxtamembrane region (34 residues to the transmembrane helix), are indicated, as are the C termini of the APS(SH2) protomers. The C-terminal tyrosine phosphorylation site in APS (Tyr-618) is 132 residues from the end of the SH2 domain.

Figure 3.
Figure 3. Mode of Binding of the IRK Activation Loop to the APS SH2 Domain(A) Stereo view of the interactions between APS(SH2) and the IRK activation loop. The IRK activation loop is colored yellow and the APS SH2 protomer to which it binds is colored green. For clarity, the other APS SH2 protomer is not shown. Hydrogen bonds/salt bridges are shown with black dashed lines.(B) Path of the IRK activation loop across the APS SH2 domain surface. A ribbon diagram of the APS SH2 dimer is shown, with the two protomers colored green and purple. The Cα trace of the IRK activation loop proximal to pTyr-1158 and pTyr-1162 is colored yellow, with the side chains of the two phosphotyrosines shown in ball-and-stick representation. The SH2 domains of Src (Waksman et al., 1993) and Grb2 (Rahuel et al., 1996) with bound peptides were superimposed (core β sheets) with the green APS SH2 protomer, and the phosphopeptides from the superposition, PQpYEEI for Src (cyan) and PSp YVNVQN for Grb2 (orange), are displayed as Cα traces, with the phosphotyrosines shown in ball-and-stick representation. The N- and C termini of the phosphopeptides are indicated by “N” and “C” of the appropriate color. The two disordered residues between βD and αB in the APS SH2 protomers are represented by small spheres.

The above figures are reprinted by permission from Cell Press: Mol Cell (2003, 12, 1379-1389) copyright 2003.