TY - JOUR
T1 - The agonist selectivity of a class III metabotropic glutamate receptor, human mGluR4a, is determined by the N-terminal extracellular domain
AU - Tones, M. A.
AU - Bendali, N.
AU - Flor, P. J.
AU - Knopfel, T.
AU - Kuhn, R.
PY - 1995/12/29
Y1 - 1995/12/29
N2 - To test the hypothesis that the determinants for agonist selectivity of class III metabotropic glutamate receptors (mGluRs) are localized in the N-terminal extracellular domain, a chimaeric cDNA was constructed where 519 amino acids of the N-terminal extracellular domain of human mGluRlb were exchanged with the corresponding region of human mGIuR4. The pharmacological profile of the chimaera, designated hmGluR41-519/1b, was analysed by recordings of intracellular calcium concentration ([Ca2+]i) in transiently transfected HEK 293 cells and compared with that of human mGluR4b and human mGluR4a stably expressed in Chinese hamster ovary cells. Application of l00μM L-2-amino-4-phosphonobu-tyrate (L-AP4), a class HI mGluR-specific agonist, induced a rise in [Ca2+]i in hmGluR41-519/1b but not in hmGluRlb expressing cells. In contrast, application of quisqualate (100/μM) induced a rise in [Ca2+]i at hmGluR1b but not at hmGluR41-519/1b. Dose-response analysis with L-AP4 and L-glutamate at hmGluR41-519/1b revealed a half-maximal effect (EC50) of 16.0/μM and 196μM, respectively. The EC50 values for quisqualate, glutamate and (1S,3R)-ACPD at hmGluRlb were 10.25 /μM, 225 fiM and 3060/μM, respectively. The rank order of agonist potency of hmGluR41-519/1b corresponds to that of hmGluR4 (L-AP4 > L-glutamate > (1S,3R)-ACPD > quisqualate) but is different from that of hmGluRlb (quisqualate > glutamate > (1S,3R)-ACPD).
AB - To test the hypothesis that the determinants for agonist selectivity of class III metabotropic glutamate receptors (mGluRs) are localized in the N-terminal extracellular domain, a chimaeric cDNA was constructed where 519 amino acids of the N-terminal extracellular domain of human mGluRlb were exchanged with the corresponding region of human mGIuR4. The pharmacological profile of the chimaera, designated hmGluR41-519/1b, was analysed by recordings of intracellular calcium concentration ([Ca2+]i) in transiently transfected HEK 293 cells and compared with that of human mGluR4b and human mGluR4a stably expressed in Chinese hamster ovary cells. Application of l00μM L-2-amino-4-phosphonobu-tyrate (L-AP4), a class HI mGluR-specific agonist, induced a rise in [Ca2+]i in hmGluR41-519/1b but not in hmGluRlb expressing cells. In contrast, application of quisqualate (100/μM) induced a rise in [Ca2+]i at hmGluR1b but not at hmGluR41-519/1b. Dose-response analysis with L-AP4 and L-glutamate at hmGluR41-519/1b revealed a half-maximal effect (EC50) of 16.0/μM and 196μM, respectively. The EC50 values for quisqualate, glutamate and (1S,3R)-ACPD at hmGluRlb were 10.25 /μM, 225 fiM and 3060/μM, respectively. The rank order of agonist potency of hmGluR41-519/1b corresponds to that of hmGluR4 (L-AP4 > L-glutamate > (1S,3R)-ACPD > quisqualate) but is different from that of hmGluRlb (quisqualate > glutamate > (1S,3R)-ACPD).
KW - Calcium
KW - Chimaeric receptors
KW - G-protein-coupled receptors
KW - Signal transduction
UR - http://www.scopus.com/inward/record.url?scp=0029554137&partnerID=8YFLogxK
U2 - 10.1097/00001756-199512290-00028
DO - 10.1097/00001756-199512290-00028
M3 - Journal article
C2 - 8742431
AN - SCOPUS:0029554137
SN - 0959-4965
VL - 7
SP - 117
EP - 120
JO - NeuroReport
JF - NeuroReport
IS - 1
ER -