Structural and biochemical evidence for an autoinhibitory role for tyrosine 984 in the juxtamembrane region of the insulin receptorLi, S., Covino, N.D., Stein, E.G., Till, J.H., Hubbard, S.R.
(2003) J Biol Chem 278: 26007-26014
- PubMed: 12707268
- DOI: https://doi.org/10.1074/jbc.M302425200
- Primary Citation of Related Structures:
- PubMed 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.
Skirball Institute of Biomolecular Medicine and Department of Pharmacology, New York University School of Medicine, New York, New York 10016, USA.