Editing of the GLuR-B ion channel RNA in vitro by recombinant double-stranded RNA adenosine deaminase.
Double-stranded RNA (dsRNA)-specific adenosine deaminase (DRADA) has been implicated as an enzyme responsible for the editing of RNA transcripts encoding glutamate-gated ion channel subunits (GLuR) in brain. In one case, the editing alters the gene-encoded glutamine (Q) to an arginine (R) located within the channel-forming domain of the alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor subunit GLuR-B. The result of editing at this site, called the 'Q/R' site, is a profound alteration of the Ca2+ permeability of the GLuR channel. Using recombinantly expressed DRADA proteins, we now demonstrate in vitro that DRADA is indeed involved in editing of the GLuR-B RNA. In addition to the formation of an RNA duplex structure involving exon and intron sequences, Q/R site-selective editing by DRADA also requires a cofactor protein(s) commonly present even in non-neuronal cells. The accuracy and efficiency of this RNA editing system appear to be determined by the quantitative balance between DRADA, cofactor and substrate GLuR-B RNA.
Dabiri
G A
GA
The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA.
Lai
F
F
Drakas
R A
RA
Nishikura
K
K
D000243:Adenosine Deaminase / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009690:Nucleic Acid Conformation; D017393:RNA Editing; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA / Q000235:genetics*
D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D018091:Receptors, AMPA; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase