Calcium discriminates two [3H]kainate binding sites with different molecular target sizes in rat cortex.
Binding of [3H]kainate to the kainate subtype of excitatory amino acid receptors revealed two binding sites. The high-affinity site (Kd = 3.5 nM) was sensitive to calcium ions and has a molecular target size as determined by high-energy radiation inactivation analysis of 76,600 daltons. The low-affinity site (Kd = 65 nM) was insensitive to calcium ions and has a molecular target size similar to the quisqualate-subtype of excitatory amino acid receptors. The change in binding parameters of the two sites with radiation dose strongly suggests that low affinity, calcium-insensitive [3H]kainate binding sites are equivalent to quisqualate sites.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000378:metabolism*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000378:metabolism*; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D008970:Molecular Weight; D051381:Rats; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000378:metabolism*
D002118:Calcium; D007608:Kainic Acid; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter