HIGHLY CONSERVED GENES-CODING FOR EUKARYOTIC TRANSLATION INITIATION-FACTOR EIF-4A OF TOBACCO HAVE SPECIFIC ALTERATIONS IN FUNCTIONAL MOTIFS

Eukaryotic translation initiation factor eIF-4A is an ATP-dependent RN A helicase that is required for the binding of mRNA to ribosomes. Plan t eIF-4A-like proteins are highly homologous to eIF-4As from yeast, mo use and Drosophila melanogaster. The pattern of intron-exon boundaries in eIF-4A-like genes are conserved within tobacco, but are not conser ved with other organisms. Fixed spacings between the functionally impo rtant sequence motifs, GKT-PTRELA (72 bp), DEAD-SAT (81 bp) and SAT-HR IGR (426 bp), are conserved between plants, mouse, Drosophila and yeas t.