Effect of chemical modification of arginyl and histidyl residues on [3H]MK-801 binding to brain synaptic membranes.
Chemical modification of the N-methyl-D-aspartate (NMDA) receptor was investigated in a thoroughly washed Triton-treated pig forebrain membrane preparation. Modification of arginyl residues using phenylglyoxal significantly reduced activation of the NMDA receptor as measured by specific binding of [3H]MK-801 [(+)-5-methyl-10,11-dihydro-dibenzo[a,d]cyclohepten-5,10-imine]. The reduction was due to a decrease in the affinity of MK-801 for its binding site from 3.2 +/- 0.5 nM to 22 +/- 8 nM. Protection studies indicated that alteration of the glutamate or glycine binding sites is not directly responsible for the effect. Diethyl pyrocarbonate treatment also reduced [3H]MK-801 binding, by modification of histidyl residues. The binding affinity was reduced to 8.3 +/- 1.4 nM whereas the Bmax was unchanged. Protection studies indicated that the modified histidine is unlikely to be a component of the glutamate, glycine or MK-801 binding sites. However, the accessibility of the modified histidine seems to be partly dependent on the activation of the receptor.
Crilley
C T
CT
Department of Biochemistry and Molecular Biology, Leeds University, U.K.
Turner
A J
AJ
D000818:Animals; D001120:Arginine / Q000737:chemistry; D001921:Brain / Q000378:metabolism*; D016291:Dizocilpine Maleate / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D066298:In Vitro Techniques; D011869:Radioligand Assay; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine; D013570:Synaptic Membranes / Q000378:metabolism*
D016194:Receptors, N-Methyl-D-Aspartate; D006639:Histidine; D016291:Dizocilpine Maleate; D001120:Arginine