1. Face‐to‐face kinase domain dimerisation of human Ire1α.
Face‐to‐face kinase domain dimerisation of human Ire1α. (A) Human Ire1α forms a dimer in which the kinase active sites of the two monomers face each other. The activation segment of one monomer is directed towards the other, so that the target substrate residue, Ser724 would come into close proximity of the Mg2+‐ATP bound in the opposite active site, and be phosphorylated by it. This arrangement of Ire1α molecules provides a straightforward mechanistic model for how dimerisation of Ire1 N‐terminal domains in the lumen of the ER would facilitate association and transphosphorylation of their associated kinase domains on the cytoplasmic side of the membrane. (B) Autophosphorylation of dephosphorylated dimer interface mutants Q636A and F637A Ire1 as compared with wild type. Both wild‐type and mutant proteins were incubated with 5 mM MgCl and 5 mM ATP at 37°C and samples were run at specific time points. Protein samples were visualised by western blot with generic Ire1α or the phospho‐specific pS724‐Ire1α.
Maruf M U Ali et al. EMBO J. 2011;30:
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