FIGURE 2.

Conserved structure of the CAPERα UHM. A, secondary structure elements of the human CAPERα UHM (residues 412–524 from NCBI RefSeq NP_004893) aligned with its primary sequence and those of representative homologues from Mus musculus (NP_573505), Xenopus laevis (NP_001086950), Drosophila melanogaster (NP_609095), Arabidopsis thaliana (AAO30095), Caenorhabditis elegans (NP_74130), Dictyostelium discoideum (XP_638966), and Schizosaccharomyces pombe (NP_594422) using Clustal Omega (56). Below, a structure-based alignment among known UHM structures is given: U2AF⁶⁵ (PDB ID 4FXW), Puf60 (PDB ID 3DXB), SPF45 (PDB ID 2PEH), and U2AF³⁵ (PDB ID 1JMT). Sequence identity is colored: <40% white; 40–54% yellow, 55–69% chartreuse, 70–84% lime, 85–99% green, and 100% forest. UHM/ULM contacts are marked by symbols (red): S, side chain hydrogen bond; M, main chain hydrogen bond; π, interaction with an aromatic residue. RNP motifs are highlighted by black lines and consensus sequence are indicated: o, aliphatic, φ, aromatic; x, any residue; L, leucine; G, glycine; +, positively-charged residue. B, ApoCAPERα UHM structure. Top, view into the RNP face. Below, surface and ball-and-stick representations of the C-terminal extension viewed following a 90° rotation about the y axis.