KAINATE RECEPTOR SUBUNITS EXPRESSED IN SINGLE CULTURED HIPPOCAMPAL-NEURONS - MOLECULAR AND FUNCTIONAL VARIANTS BY RNA EDITING

To determine the kainate receptor subunits that are found in native ka inate receptors, we have applied a multiplex PCR of cDNAs reverse tran scribed from mRNA harvested from single cultured hippocampal neurons a fter electrophysiological recording. We found that all the cells showi ng rapidly desensitizing currents in response to kainate express the G luR6 subunit mRNA, and that some of them also express the GluRS subuni t mRNA. No GluR7, KA-1, or KA-2 subunit mRNAs were detected. Analysis of the editing sites of the GluR6 mRNA demonstrated that the three edi ting sites present in these subunits are edited to a different extent. Predominant expression of the unedited variant (Q) was observed, but edited and unedited variants may coexist in the same cell. In addition , we show that the Q/R site from the GluR6 subunit controls functional properties of native kainate receptors.