RIBIOP_C is a family of eukaryotic proteins from the C-terminus of pre-rRNA-processing protein or ribosome biogenesis proteins BMS1 and TSR1. These proteins act, in the nucleolus, as a molecular switch during maturation of the 40S ribosomal subunit [1,2]. This domain, domain IV of translation elongation factor selb, adopts the same fold as translation proteins such as domain II of GTP-elongation factor Tu proteins [3].

1: Bms1p, a novel GTP-binding protein, and the related Tsr1p are required for distinct steps of 40S ribosome biogenesis in yeast. Gelperin D, Horton L, Beckman J, Hensold J, Lemmon SK; RNA. 2001;7:1268-1283. PMID:11565749

2: Bms1p, a G-domain-containing protein, associates with Rcl1p and is required for 18S rRNA biogenesis in yeast. Wegierski T, Billy E, Nasr F, Filipowicz W; RNA. 2001;7:1254-1267. PMID:11565748

3: Selenocysteine tRNA-specific elongation factor SelB is a structural chimaera of elongation and initiation factors. Leibundgut M, Frick C, Thanbichler M, Bock A, Ban N; EMBO J. 2005;24:11-22. PMID:15616587