Title : Structure and assembly mechanism for heteromeric kainate
receptors
Abstract :
- Native glutamate receptor ion channels are tetrameric assemblies containing two or more different subunits
- NMDA receptors are obligate heteromers formed by coassembly of two or three divergent gene families
- While some AMPA and kainate receptors can form functional homomeric ion channels , the KA1 and KA2 subunits are obligate heteromers which function only in combination with GluR5-7
- The mechanisms controlling glutamate receptor assembly involve an initial step in which the amino terminal domains ( ATD ) assemble as dimers
- Here, we establish by sedimentation velocity that the ATDs of GluR6 and KA2 coassemble as a heterodimer of K(d) 11 nM, 32,000-fold lower than the K(d) for homodimer formation by KA2 ; we solve crystal structures for the GluR6 / KA2 ATD heterodimer and heterotetramer assemblies
- Using these structures as a guide, we perform a mutant cycle analysis to probe the energetics of assembly and show that high-affinity ATD interactions are required for biosynthesis of functional heteromeric receptors
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