| pubmed-article:1381042 | pubmed:abstractText | Kainate receptors from goldfish brain were purified by affinity chromatography. Unlike previously published purifications, which have yielded single proteins of 48-50 kDa from frog, chick, and pigeon brain, our preparations contained two polypeptides, of 41 kDa and 45 kDa. In addition, a broad band centered at 120 kDa was present. Some of the 41-kDa and 45-kDa polypeptides were derived from the higher molecular mass protein. All of these proteins were recognized by a monoclonal antibody produced against a purified frog kainate receptor. The distribution of the 41-kDa and 45-kDa proteins varied independently in different major brain regions, suggesting that they can exist as separate independent proteins. A partial amino acid sequence of the 41-kDa polypeptide is very similar (40-60% identity) to specific segments of the frog and chick kainate-binding proteins and the alpha-amino-3-hydroxy-5-methylisoxazolepropionate/kainate ion channels. The characteristics of the 41-kDa and 45-kDa polypeptides suggest that these two proteins are distinct. Photo-affinity labeling with [3H]kainate showed that a [3H]kainate binding site is associated with the 41-kDa polypeptide, and peptide mapping suggests that the two proteins are not identical. In addition, the two peptides do not appear to be related by differential glycosylation or phosphorylation. The 41-kDa and 45-kDa polypeptides, therefore, appear to be distinct and may represent kainate receptor subtypes or, in some cases, possibly two different subunits of a kainate receptor complex. | lld:pubmed |
