A tumour-associated DEAD-box protein, rck/p54 exhibits RNA unwinding activity toward c-myc RNAs in vitro

Background: The rck/p54 protein of 473 amino acids belongs to the family of DEAD-box/putative RNA helicase proteins. DEAD-box proteins have been implicated in a wide variety of cellular processes ranging from the initiation of protein synthesis and ribosome biosynthesis to premRNA splicing by means of modifying the RNA structure. Our previous data suggested that rck/p54 positively affected the translation initiation of c-myc mRNA. Results: The data obtained from morphological studies and surface plasmon resonance assays clearly indicated that the protein specifically bound to c-myc RNA transcripts (RNAs) and exhibited RNA unwinding activity toward c-myc RNAs in the presence of ATP in vitro . Experiments using a deletion mutant of rck/p54 retaining only its N-terminal 289 amino acids demonstrated that the deleted C-terminal 184 amino acid domain is involved in the RNA unwinding activity. Conclusion: These findings strongly suggest that rck/p54 may play an important role in translation initiation by restructuring mRNAs even in the cell and contribute to carcinogenesis.