Crystal structure of the activated insulin receptor tyrosine kinase in complex with peptide substrate and ATP analog

Abstract

The crystal structure of the phosphorylated, activated form of the insulin receptor tyrosine kinase in complex with a peptide substrate and an ATP analog has been determined at 1.9 Å resolution. The activation loop (A‐loop) of the kinase undergoes a major conformational change upon autophosphorylation of Tyr1158, Tyr1162 and Tyr1163 within the loop, resulting in unrestricted access of ATP and protein substrates to the kinase active site. Phosphorylated Tyr1163 (pTyr1163) is the key phosphotyrosine in stabilizing the conformation of the tris‐phosphorylated A‐loop, whereas pTyr1158 is completely solvent‐exposed, suggesting an availability for interaction with downstream signaling proteins. The YMXM‐containing peptide substrate binds as a short anti‐parallel β‐strand to the C‐terminal end of the A‐loop, with the methionine side chains occupying two hydrophobic pockets on the C‐terminal lobe of the kinase. The structure thus reveals the molecular basis for insulin receptor activation via autophosphorylation, and provides insights into tyrosine kinase substrate specificity and the mechanism of phosphotransfer.

Point mutations in the tyrosine kinase domain release the oncogenic and metastatic potential of the ron receptor

“…The occurrence of constitutively autophosphorylated receptor indicates that the tyrosine kinase activity is blocked in a noninhibitory condition, responsible for continuous downstream signalling to the nucleus (Hubbard et al, 1994;Mohammadi et al, 1996;Hubbard, 1997). Here we show that Ron receptor mutants are constitutively phosphorylated on tyrosine, as revealed by antiphosphotyrosine antibodies.…”

Acidic substitution of the activation loop tyrosines in TrkA supports nerve growth factor-independent cell survival and neuronal differentiation

“…These observations suggest a model of TrkA activation based on crystallographic analyses of the IRK (Hubbard et al, 1994;Hubbard, 1997). Accordingly, Tyr 683 in TrkA is thought to be involved in auto-inhibition of the receptor in the absence of ligand.…”

“…While the intracellular domain of TrkA has not been crystallized, studies on the b-chain of the IRK (Hubbard et al, 1994;Hubbard, 1997) have provided (Hubbard, 1997). Finally, Tyr 679 in TrkA (Tyr 1158 in the IRK) is predicted to be solvent exposed in an active conformation (Hubbard, 1997) suggesting a possible role in substrate interaction.…”

“…Finally, Tyr 679 in TrkA (Tyr 1158 in the IRK) is predicted to be solvent exposed in an active conformation (Hubbard, 1997) suggesting a possible role in substrate interaction.…”

“…Interestingly, the double substitution mutants that contain at least one glutamate residue retain signi®cant biological responsiveness in comparison with AspAsp. The apparent preference for glutamic acid at either Tyr 683 or Tyr 684 may re¯ect the fact that both pTyr residues are predicted to participate in salt bridge formation in an active state (Hubbard, 1997); thus, the longer carbon side chain of glutamate may facilitate this process. Since GluAsp and AspGlu receptors retain kinase activities that are only 30 ± 35% of wild type…”