title: Double-stranded-RNA-dependent protein kinase and TAR RNA-binding protein form homo- and heterodimers in vivo.
abstract: The yeast two-hybrid system and far-Western protein blot analysis were used to demonstrate dimerization of human double-stranded RNA (dsRNA)-dependent protein kinase (PKR) in vivo and in vitro. A catalytically inactive mutant of PKR with a single amino acid substitution (K296R) was found to dimerize in vivo, and a mutant with a deletion of the catalytic domain of PKR retained the ability to dimerize. In contrast, deletion of the two dsRNA-binding motifs in the N-terminal regulatory domain of PKR abolished dimerization. In vitro dimerization of the dsRNA-binding domain required the presence of dsRNA. These results suggest that the binding of dsRNA by PKR is necessary for dimerization. The mammalian dsRNA-binding protein TRBP, originally identified on the basis of its ability to bind the transactivation region (TAR) of human immunodeficiency virus RNA, also dimerized with itself and with PKR in the yeast assay. Taken together, these results suggest that complexes consisting of different combinations of dsRNA-binding proteins may exist in vivo. Such complexes could mediate differential effects on gene expression and control of cell growth.
authors.affiliation: Department of Biochemistry, McGill University, Montreal, QC Canada.
authors.forename: G P
authors.initials: GP
authors.lastname: Cosentino
authors.forename: S
authors.initials: S
authors.lastname: Venkatesan
authors.forename: F C
authors.initials: FC
authors.lastname: Serluca
authors.forename: S R
authors.initials: SR
authors.lastname: Green
authors.forename: M B
authors.initials: MB
authors.lastname: Mathews
authors.forename: N
authors.initials: N
authors.lastname: Sonenberg
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D015533:Transcriptional Activation; D019892:eIF-2 Kinase; D000099253:Trans-Activation Responsive RNA-Binding Protein
chemical_list: D017346:Protein Serine-Threonine Kinases; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D019892:eIF-2 Kinase; D000099253:Trans-Activation Responsive RNA-Binding Protein