Molecular mechanism of calcium permeability and magnesium block in NMDA receptors.
Level 5 - mechanism / opinion, no new human data
In vitro structural biology bench research (single-particle cryo-EM)
PubMed 42086762 · doi:10.1038/s41593-026-02283-3
What was done
The authors used single-particle cryo-electron microscopy (cryo-EM) to investigate the structural mechanisms of calcium (Ca2+) permeation and magnesium (Mg2+) channel blockade in N-methyl-D-aspartate (NMDA) glutamate receptors.
What was found
The abstract reports qualitative structural mechanisms and contains no quantitative values: - Ca2+ permeation through the narrow selectivity filter involves partial dehydration across several identified Ca2+ binding sites. - Mg2+ binds outside the selectivity filter via a coordinating water network, remaining hydrated and acting as a physical channel blocker. - A lipid network surrounding the selectivity filter modulates the stability of Mg2+ binding in a voltage-dependent manner.
Why it matters
It resolves the long-standing structural basis for how NMDA receptors achieve Ca2+ selectivity while maintaining voltage-dependent Mg2+ block, key biophysical mechanisms underlying Hebbian synaptic plasticity.
Limits
The abstract reports no numerical metrics (e.g., resolution, particle counts, or affinity constants). Findings are based on in vitro structural snapshots from cryo-EM, which do not directly measure real-time ion flux or dynamic functional kinetics in native cellular environments.
Cited by
- supports Magnesium acts as a cofactor at glutamate receptors to turn down neuronal excitation.