Sequence architecture of RBR proteins. The detailed sequence architecture of the subfamilies of RBR proteins is shown. The globular domains (such as cullin) and non-globular regions (negative-charge clusters or proline-rich regions) are color-coded as shown in the key. It should be noted that the typical sequence architecture is shown. There are several exceptions: for example, PAUL proteins mostly contain three additional zinc fingers, but a few representatives have only one. Similarly, dorfins have two predicted hydrophobic helices with the exception of the protozoan members, which have only one or none. The two sequences of the Fungi1 group are very diverse and have only the RBR segment in common. Among the Plant1 representatives, one protein contains two RRM domains instead of the usual two KH domains. Domain accession numbers: APC10, PF03256; cullin, SM00182; DEXDc, SM00487; IBR, SM00647; RWD, SM00591; DUF1605, PF07717; HA2, PF04408; HELICc, SM00490; KH, SM00322; RRM, SM 00360; ANK, SM002481; UBA, SM00165; UBQ, SM00213; UIM, SM00726; and ZnF_RBZ, SM00547. The first two letters 'PF' and 'SM' indicate the PFAM and SMART databases, respectively.