Structural organization of the human gene (PKR) encoding an interferon-inducible RNA-dependent protein kinase (PKR) and differences from its mouse homolog.

The gene encoding the interferon-inducible, RNA-dependent protein kinase (PKR) was isolated as lambda phage and P1 phage clones from human genomic DNA libraries and characterized by Southern blot and nucleotide sequence analyses. Southern blot analyses were consistent with a single PKR gene, and genomic clones colocalized by fluorescence in situ hybridization to human chromosome 2p. Sequence analysis demonstrated that the human PKR gene consists of 17 exons and spans about 50 kb. The AUG translation initiation site for the 551-amino-acid PKR protein was located in exon 3; exon 17 was the largest exon and included the UAG translation termination site, AUUAAA polyadenylation signal, and putative C(A) 3' cleavage site. Two RNA-binding motifs, RI and RII, were present in exons 4 and 6, respectively, and the codon phasing of these exon junctions was conserved between them. The organization of the regulatory and catalytic subdomains of the PKR protein was remarkably preserved between the human and the mouse PKR genes; the amino acid junction positions for 13 of the 15 protein coding exons were exactly conserved.