FIG. 2.

The MOG-1 protein. (A) Predicted amino acid sequence of MOG-1 and comparison with that of PRP16. Identical amino acids are boxed. We chose to compare MOG-1 to PRP16 and not PRP43 because of their similar sizes (PRP43 is only 767 amino acids long). In the N-terminal part of the protein is the arginine-serine (RS)- and arginine-aspartic acid (RD)-rich region (white letters on black background). The conserved region of each member of the broad family including DEAD- and DEXH-box proteins spans amino acids 474 to 773 and includes five stretches of conserved amino acids (underlined) (33). The first of these stretches, GETGSGKTTQ, contains the A site of the nucleoside triphosphate-binding and ATPase motif; the ATPase B site corresponds to the DEAH motif. In addition to these broadly conserved regions, numerous amino acids (gray shading) are conserved in all 12 DEAH-box proteins examined: human (HRH1 and hPRP16), S. cerevisiae (PRP2, PRP16, PRP22, and PRP43), Saccharomyces pombe (Cdc28), C. elegans (MOG-1, F56D2.6, and EEED8.5), and Arabidopsis thaliana (accession no. X98130 and Z97341). This region of high-level conservation spans amino acids 434 to 1051 in MOG-1. The 12 selected sequences for this comparison correspond to the 12 best scores obtained by the BLASTp program, using MOG-1 as the query. Black dots indicate the positions of mutations in mog-1. The three nonsense mutations, q151, q370, and q223, are at positions 221 (ochre), 330 (opal), and 473 (amber), respectively, and the one missense mutation, q473, is at position 777 (arginine to histidine). Putative nuclear localization signals in MOG-1 are indicated as full lines overlying the sequence. (B) Comparison of MOG-1 to other DEAH-box proteins. The mog-1 amino acid sequence was compared to GenBank-PDB-SwissProt-PIR database sequences by using the BLASTp program. Only DEAH-box proteins had a high level of similarity. We have provided data for the best-understood ones as well as for one DEIH protein, the Drosophila protein Maleless (27). Other proteins with a similar degree of sequence identity but no functional information are not listed; two are from C. elegans (F56D2.6 and EEED8.5) and two are from A. thaliana (accession no. X98130 and Z97341). EEED8.5, F56D2.6 (C. elegans), HRH1 (human), hPRP16 (human), and Z97341 (A. thaliana) each contains an extensive RS domain located in the N terminus (data not shown). Like Maleless (a DEIH-box protein), other DEXX putative helicases are much less similar to MOG-1 than DEAH-box proteins; Xenopus laevis eIF4A (a DEAD-box protein) and Drosophila Homeless (a DEVH-box protein) do not align with MOG-1, indicating a distant relationship. The conserved region consists of amino acids corresponding to residues 434 to 1051 of MOG-1.