IDENTIFICATION OF BOVINE GLUTAMATE-DEHYDROGENASE AS AN RNA-BINDING PROTEIN

Two RNA binding activities were demonstrated in bovine liver homogenat e. One binding protein was isolated by a simple ion exchange and gel f iltration protocol and was shown by N-terminal protein sequence analys is to be glutamate dehydrogenase. Using identical RNA substrate and as say conditions, no detectable RNA binding was observed with equimolar amounts of other representative dehydrogenases and proteins. Furthermo re, excesses of tRNA, salmon testis DNA, or each of the four homoribop olymers were unable to compete for the RNA-binding site. Total cytosol ic RNA, however, successfully prevented binding of radiolabeled RNA su bstrate. These data are consistent with glutamate dehydrogenase contai ning a binding site for heteropolymeric RNA with highest affinity for an as yet undefined nucleotide consensus sequence or structure. The po tential physiological relevance of these observations is discussed.