Figure 3.

Schematic of the surprisingly complex biogenesis of H/ACA RNPs. Details of the at least 4-step process are described in the text. The approximate size and sites of interactions of the proteins is drawn to scale. Inset: Surface rendering of the structures of yeast NAP57 alone and in complex with the SHQ1 specific domain (SSD; pdb: 3uai). Amino acid positions equivalent to those mutated in human NAP57 in patients with dyskeratosis congenita are highlighted (orange). Note many of these positions cluster in the C-terminal segment (CTS, knob on the left) that serves as handle for the SSD, although they are generally poorly visible in this surface rendering.