glycine binding in the NMDA channel

Dr Thomas Salt smgxt01 at ucl.ac.uk
Tue Nov 9 06:33:26 EST 1993


markb at orl.mmc.com (Mark Bower) writes:

>A few days ago, there was some discussion about the function/necessity of
>glycine binding in the NMDA channel. The discussion acknowledged the fact
>that glycine is indeed necessary for channel operation, but considered it
>to be a non-issue due it's the high extracellular concentration. However,

I'm afraid I missed the original discussion on this topic, so please
forgive me if this is a repeat of a previous point.  However, it
seems to me that nobody knows what the glycine concentration at the
NMDA receptor _in_vivo_ may be, and there is no reason to assume that
this would be the same as the 'mean' extracellular concentration, as
there are active trasnport processes for this amino acid which may
regulate glycine levels locally.  Far more telling is the finding by
several workers (including myself) that glycine or D-serine can
enhance NMDA responses under physiological conditions: this implies
that the glycine site on the NMDA receptor is not saturated under
physiological conditions.


Tom Salt.



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