Figure 6: Structure of an archaeal box H/ACA sRNP (adapted from [52]). (a) The surface representation of the X-ray crystal structure of P. furiosus box H/ACA sRNP. The catalytic domain of Cbf5 (Cbf5-Cat) is in dark green, the PUA domain (Cbf5-PUA) is in light green, L7Ae is in blue, Nop10 is in magenta, Gar1 is in cyan, sRNA guide sequence is in orange, box ACA is in red, the remainder of the sRNA is in yellow, and the substrate RNA is in red. (b) Comparison of conformations of the thumb loop in the substrate-bound and the substrate-free state. The thumb loop conformation in the substrate-free state is in gray and that in the substrate-bound state is in green.