The N-methyl-D-aspartate receptor channel complex and the σ site have different target sizes

Abstract

Radiation inactivation technique has been used to measure the molecular sizes of the N-methyl-D-aspartate (NMDA) receptor and the σ recognition site. Target size analysis of [ 3H]MK-801 (dizocilpine maleate) binding to the NMDA receptor channel complex in rat cortical membranes has given a molecular size of 128 000 ± 9000 Da. This is in contrast to the target size of the σ site in the same tissue as labelled by [ 3H]DTG (ditolylguanidine), giving a value of 36 000 ± 2900 Da. These studies have provided evidence for a clear difference in the molecular sizes of these two recognition sites.