In addition to the orthosteric  site (the site where the endogenous ligand glutamate binds) at least two distinct allosteric binding sites exist on the mGluR1.
A respectable number of potent and specific allosteric ligands – predominantly antagonists/inhibitors – has been developed in recent years, although no orthosteric subtype-selective ligands have yet been discovered (2008).

JNJ-16259685: highly potent, selective non-competitive antagonist
R-214,127 and [³H]-analog: high-affinity,  selective allosteric inhibitor
YM-202,074: high-affinity, selective allosteric antagonist
YM-230,888: high-affinity, selective allosteric antagonist
YM-298,198 and [³H]-analog: selective non-competitive antagonist
FTIDC:  highly potent and selective allosteric antagonist/inverse agonist
A-841,720: potent non-competitive antagonist; minor hmGluR5 binding
VU-71: potentiator
Fluorinated 9H-xanthene-9-carboxylic acid oxazol-2-yl-amides: orally available PAMs
Cyclothiazide: non-selective non-competitive antagonist
In addition to the orthosteric  site (the site where the endogenous ligand glutamate binds) at least two distinct allosteric binding sites exist on the mGluR1. A respectable number of potent and specific allosteric ligands – predominantly antagonists/inhibitors – has been developed in recent years, although no orthosteric subtype-selective ligands have yet been discovered (2008).
JNJ-16259685: highly potent, selective non-competitive antagonist
R-214,127 and [³H]-analog: high-affinity,  selective allosteric inhibitor
YM-202,074: high-affinity, selective allosteric antagonist
YM-230,888: high-affinity, selective allosteric antagonist
YM-298,198 and [³H]-analog: selective non-competitive antagonist
FTIDC:  highly potent and selective allosteric antagonist/inverse agonist
A-841,720: potent non-competitive antagonist; minor hmGluR5 binding
VU-71: potentiator
Fluorinated 9H-xanthene-9-carboxylic acid oxazol-2-yl-amides: orally available PAMs
Cyclothiazide: non-selective non-competitive antagonist
Metabotropic glutamate receptor 1