| Type: | Domain | Name: | Bms1/Tsr1-type G domain |
| Description: | Bms1p and Tsr1p represent a new family of factors required for ribosome biogenesis. They are each independently required for 40S ribosomal subunitbiogenesis. Bms1p, a protein required for pre-rRNA processing, contains an evolutionarily conserved guanine nucleotide-binding (G) domain with five conserved polypeptide loopsdesignated G1 through G5, which form contact sites with the guanine nucleotide or coordinate the Mg(2+) ion. Sequences resembling G1 (consensus [GA]-x(4)-G- K-[ST]; also known as a P-loop), G4 (consensus [NT]-K-x-D), and G5 (consensusS-[AG] are present in all Bms1 proteins, and either fully conform with theconsensus or contain, at most, single conservative substitutions. The G2 motif (consensus G-P-[IV]-T) contains a T residue involved in the coordination of the Mg(2+) required for GTP hydrolysis. The G3 motif diverges from theconsensus found in G proteins, D-x(2)-G; however, the D residue is replaced with the conserved E residue. In contrast, Tsr1p lacks a P-loop and is notpredicted to bind GTP. It functions at a later step of 40S ribosome production, possibly in assembly and/or export of 43S pre-ribosomal subunitsto the cytosol [, , ].This entry represents a domain found in Bms1 and Tsr1, and includes cases, such as Tsr1, where it may not function as a guanine nucleotide-binding domain. | Short Name: | G_Bms1/Tsr1_dom |
