PDBsum entry 3bu6

Transferase

PDB id: 3bu6

Contents

Protein chains

297 a.a.

14 a.a.

Waters ×213

References listed in PDB file

Key reference

Title

Structural and biochemical characterization of the krlb region in insulin receptor substrate-2.

Authors

J.Wu, Y.D.Tseng, C.F.Xu, T.A.Neubert, M.F.White, S.R.Hubbard.

Ref.

Nat Struct Mol Biol, 2008, 15, 251-258. [DOI no: 10.1038/nsmb.1388]

PubMed id

18278056

Abstract

Insulin receptor substrates 1 and 2 (IRS1 and -2) are crucial adaptor proteins in mediating the metabolic and mitogenic effects of insulin and insulin-like growth factor 1. These proteins consist of a pleckstrin homology domain, a phosphotyrosine binding domain and a C-terminal region containing numerous sites of tyrosine, serine and threonine phosphorylation. Previous yeast two-hybrid studies identified a region unique to IRS2, termed the kinase regulatory-loop binding (KRLB) region, which interacts with the tyrosine kinase domain of the insulin receptor. Here we present the crystal structure of the insulin receptor kinase in complex with a 15-residue peptide from the KRLB region. In the structure, this segment of IRS2 is bound in the kinase active site with Tyr628 positioned for phosphorylation. Although Tyr628 was phosphorylated by the insulin receptor, its catalytic turnover was poor, resulting in kinase inhibition. Our studies indicate that the KRLB region functions to limit tyrosine phosphorylation of IRS2.

Figure 1.
Domain organization and location of tyrosine-phosphorylation sites are drawn to linear scale (mouse numbering, 1,321 residues). Tyrosine-phosphorylation sites that are recruitment sites for PI3K (Y XM motif) are labeled by ^*, the GRB2 site (Y911) is labeled by † and the two SHP2 sites (Y1242 and Y1303) are labeled by §. The KRLB region as determined by Y2H studies (residues 591–733) is shown with dashed lines, and the 15-residue region that was cocrystallized with IRK is shown in the gray box, with the sequence expanded below and Tyr628 underlined. The corresponding 15-residue sequence in IRS1 (mouse) is also shown.

Figure 2.
(a) IRK is shown as a molecular surface, with the N lobe colored dark gray and the C lobe colored light gray. The activation loop (residues 1150–1171) is colored green and the catalytic loop (residues 1130–1137) is colored orange. IRS2 KRLB^Y628 is shown in stick representation. The final 2F[o] - F[c] electron density (1.65-Å resolution, 1 contour) is shown in blue mesh. The N and C termini of the peptide are labeled.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Mol Biol (2008, 15, 251-258) copyright 2008.