TABLE 4. Metabotropic glutamate receptorsa

Subgroup

Gene

Effector system

Agonist selectivity

I

mGluR1

mGluR5

Stimulates phospholipase C

QA > Glu {ewc MVIMG, MVIMAGE,!greateq.bmp} Ibo > t-ACPD >> AP4

II

mGluR2

mGluR3

Inhibits adenylate cyclase

Glu {ewc MVIMG, MVIMAGE,!greateq.bmp} t-ACPD > Ibo >> QA >> AP4

III

mGluR4

mGluR6

Inhibits adenylate cyclase

Ap4 > Glu > SOP > ACPD > QA > Ibo AP4 > SOP > Glu. >> ACPD > QA/Ibo

a The six metabotropic glutamate receptor subtypes have been classified into three subgroups based upon similarities in their sequence homology, effector coupling in artificial expression systems, and agonist selectivity. In addition to those shown above, other coupling mechanisms have been characterized, including stimulation of cyclic AMP accumulation, stimulation of arachadonic acid metabolism, inhibition of cation channels, and stimulation of phospholipase D. Adapted from refs. 29 and 67.
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published 2000