RNA secondary structure is a critical determinant of RNA function in ribosome 
assembly, pre-mRNA splicing, mRNA translation and RNA stability. The 'DEAD/H' 
family of putative RNA helicases may help regulate these processes by utilizing 
intrinsic RNA-dependent ATPase activity to catalyze conformational changes in 
RNA secondary structure. To investigate the repertoire of DEAD/H box proteins 
expressed in mammals, we used PCR techniques to clone from mouse erythroleukemia 
(MEL) cells three new DEAD box cDNAs with high similarity to known yeast 
(Saccharomyces cerevisiae) genes. mDEAD2 and mDEAD3 (mouse DEAD box proteins) 
are > 95% identical to mouse PL10 but exhibit differential tissue-specific 
expression patterns; mDEAD2 and mDEAD3 are also approx. 70% identical (at the aa 
level) to yeast DED1 and DBP1 proteins. Members of this DEAD box subclass 
contain C-terminal domains with high content of Arg, Ser, Gly and Phe, 
reminiscent of the RS domain in several Drosophila and mammalian splicing 
factors. mDEAD5 belongs to a second class related to translation initiation 
factors from yeast (TIF1/TIF2) and mammals (eIF-4A); this class contains a novel 
conserved peptide motif not found in other DEAD box proteins. Northern blotting 
shows that mDEAD5 is differentially expressed in testis vs. somatic tissues. 
Thus, mouse erythroid cells produce two highly conserved families of putative 
RNA helicases likely to play important roles in RNA metabolism and gene 
expression.