PDBsum entry 1p14

Transferase

PDB id: 1p14

Contents

Protein chain

287 a.a. *

Waters ×188

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Structural and biochemical evidence for an autoinhibitory role for tyrosine 984 in the juxtamembrane region of the insulin receptor.

Authors

S.Li, N.D.Covino, E.G.Stein, J.H.Till, S.R.Hubbard.

Ref.

J Biol Chem, 2003, 278, 26007-26014. [DOI no: 10.1074/jbc.M302425200]

PubMed id

12707268

Abstract

Tyrosine 984 in the juxtamembrane region of the insulin receptor, between the transmembrane helix and the cytoplasmic tyrosine kinase domain, is conserved among all insulin receptor-like proteins from hydra to humans. Crystallographic studies of the tyrosine kinase domain and proximal juxtamembrane region reveal that Tyr-984 interacts with several other conserved residues in the N-terminal lobe of the kinase domain, stabilizing a catalytically nonproductive position of alpha-helix C. Steady-state kinetics measurements on the soluble kinase domain demonstrate that replacement of Tyr-984 with phenylalanine results in a 4-fold increase in kcat in the unphosphorylated (basal state) enzyme. Moreover, mutation of Tyr-984 in the full-length insulin receptor results in significantly elevated receptor phosphorylation levels in cells, both in the absence of insulin and following insulin stimulation. These data demonstrate that Tyr-984 plays an important structural role in maintaining the quiescent, basal state of the insulin receptor. In addition, the structural studies suggest a possible target site for small molecule activators of the insulin receptor, with potential use in the treatment of noninsulin-dependent diabetes mellitus.

Figure 2.
FIG. 2. Crystal structure of IRKD1132N. A, 2F[o] - F[c] electron density map (1.9 Å resolution, 1 contour) is shown in wire mesh (purple) in the region of Tyr-984. The superimposed refined structure of IRKD1132N is shown in stick representation, with the proximal juxtamembrane region (residues 978-988) colored orange, residues in C colored yellow, and residues in the sheet (and connecting loops) colored cyan. Ordered water molecules are indicated with red spheres. Selected residues are labeled. B, ribbon diagram of the IRKD1132N structure. strands are colored cyan, and -helices are colored yellow. The proximal juxtamembrane region including Tyr-984 is colored orange, with the side chain of Tyr-984 shown in ball-and-stick representation, and C in the N-terminal lobe is labeled. The dashed gray line indicates that the activation loop is disordered (from Met-1153 through Leu-1171). The N and C termini are denoted by N and C.

Figure 3.
FIG. 3. Conformation of the proximal juxtamembrane region in IRK. Stereo views of the proximal juxtamembrane region and the N-terminal kinase lobe from the IRKD1132N structure (A) and the tris-phosphorylated IRKY984F structure (13) (B) are shown. The view is from above with respect to the view in Fig. 3. The juxtamembrane region is shown in ball-and-stick representation with carbon atoms colored orange, nitrogen atoms colored blue, and oxygen atoms colored red. The side chains of selected residues of the N-terminal kinase lobe are shown in ball- and-stick representation with carbon atoms colored gray, nitrogen atoms colored blue, and oxygen atoms colored red. Semi-transparent van der Waals' surfaces in A indicate hydrophobic packing of Tyr-984 with Leu-1045 and Val-1065. C, schematic diagram (approximate spatial layout) showing the invariant residues in the insulin receptor subfamily that form the Tyr-984 binding pocket. The residue labels are placed alongside the C atoms of the side chains. The backbone nitrogen atoms of Trp-989 and Ser-1067 are included as well as the carbonyl oxygen of nonconserved Val-985 (dark gray). Hydrogen bonds are depicted by dashed lines, and van der Waals' interactions (<3.8 Å) with Tyr-984 are depicted as concentric half-circles.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 26007-26014) copyright 2003.