Figure 2.

A. Structure of representative molecules from the 4 polyoxygenated steroid classes. B. Schematic diagram illustrating characteristic domains that comprise DEAD-box RNA helicases with functions of the motifs indicated. Primary amino acid sequence of conserved motifs V and VI (indicated by overline) and neighboring amino acids of the indicated helicases. Direct protein-hippuristanol NOEs are highlighted in bold and light blue and those within ∼5Å are in orange shading.