InterPro domain: IPR028364

This entry also matches ribosome biogenesis proteins, such as Cic1, which associates with the proteasome and is required for the degradation of specific substrates [ 1 ], and for the synthesis of 60S ribosome subunits [ 2 ].

Ribosomal protein L1 is the largest protein from the large ribosomal subunit. The L1 protein contains two domains: 2-layer alpha/beta domain and a 3-layer alpha/beta domain (interrupts the first domain). The two domains cycle between open and closed conformations via a hinge motion. In Escherichia coli, L1 is known to bind to the 23S rRNA. The RNA-binding site of L1 is highly conserved, with both mRNA and rRNA binding the same binding site. Like several other large ribosomal subunit proteins, L1 displays RNA chaperone activity [ 3 , 4 , 5 , 6 , 7 , 8 ]. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities [ 9 , 10 ], groups:

• Eubacterial L1
• Algal and plant chloroplast L1
• Cyanelle L1
• Archaebacterial L1
• Vertebrate L10A
• Yeast Utp30, Rpl1a, Rpl1b and Mrpl1.

1. Cic1, an adaptor protein specifically linking the 26S proteasome to its substrate, the SCF component Cdc4. EMBO J. 20, 4423-31
2. Cic1p/Nsa3p is required for synthesis and nuclear export of 60S ribosomal subunits. RNA 9, 1431-6
3. RNA chaperone activity of L1 ribosomal proteins: phylogenetic conservation and splicing inhibition. Nucleic Acids Res. 35, 3752-63
4. Ribosomal protein L1 recognizes the same specific structural motif in its target sites on the autoregulatory mRNA and 23S rRNA. Nucleic Acids Res. 33, 478-85
5. New insights into the interaction of ribosomal protein L1 with RNA. J. Mol. Biol. 355, 747-59
6. Structure of ribosomal protein L1 from Methanococcus thermolithotrophicus. Functionally important structural invariants on the L1 surface. Acta Crystallogr. D Biol. Crystallogr. 58, 1023-9
7. Archaeal ribosomal protein L1: the structure provides new insights into RNA binding of the L1 protein family. Structure 8, 363-71
8. Structure of the L1 protuberance in the ribosome. Nat. Struct. Biol. 10, 104-8
9. Crystal structure of the RNA binding ribosomal protein L1 from Thermus thermophilus. EMBO J. 15, 1350-9
10. The primary structure of rat ribosomal protein L10a. Biochem. Biophys. Res. Commun. 220, 954-7