Summary: Ribosomal protein S18
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Ribosomal protein S18 Provide feedback
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External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR001648
Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites [PUBMED:11297922, PUBMED:11290319]. About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to - the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.
Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome [PUBMED:11290319, PUBMED:11114498].
Evidence suggests that, in prokaryotes, the peptidyl transferase reaction is performed by the large subunit 23S rRNA, whereas proteins probably have a greater role in eukaryotic ribosomes. Most of the proteins lie close to, or on the surface of, the 30S subunit, arranged peripherally around the rRNA [PUBMED:9281425]. The small subunit ribosomal proteins can be categorised as primary binding proteins, which bind directly and independently to 16S rRNA; secondary binding proteins, which display no specific affinity for 16S rRNA, but its assembly is contingent upon the presence of one or more primary binding proteins; and tertiary binding proteins, which require the presence of one or more secondary binding proteins and sometimes other tertiary binding proteins.
The small ribosomal subunit protein S18 is known to be involved in binding the aminoacyl-tRNA complex in Escherichia coli [PUBMED:2647521], and appears to be situated at the tRNA A-site. Experimental evidence has revealed that S18 is well exposed on the surface of the E. coli ribosome, and is a secondary rRNA binding protein [PUBMED:9371771]. S18 belongs to a family of ribosomal proteins [PUBMED:2179947] that includes: eubacterial S18; metazoan mitochondrial S18, algal and plant chloroplast S18; and cyanelle S18.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||ribosome (GO:0005840)|
|Molecular function||structural constituent of ribosome (GO:0003735)|
|Biological process||translation (GO:0006412)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
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This family contains a diverse range of mostly DNA-binding domains that contain a helix-turn-helix motif.
The clan contains the following 340 members:AbiEi_3_N AbiEi_4 ANAPC2 AphA_like Arg_repressor ARID ArsR B-block_TFIIIC B5 Bac_DnaA_C Baculo_PEP_N BetR BHD_3 BLACT_WH Bot1p BrkDBD BsuBI_PstI_RE_N C_LFY_FLO CaiF_GrlA CarD_CdnL_TRCF CDC27 Cdc6_C Cdh1_DBD_1 CDT1 CDT1_C CENP-B_N Costars CPSase_L_D3 Cro Crp CSN4_RPN5_eIF3a CSN8_PSD8_EIF3K CtsR Cullin_Nedd8 CUT CUTL CvfB_WH DBD_HTH DDRGK DEP Dimerisation Dimerisation2 DNA_meth_N DpnI_C DprA_WH DsrC DsrD DUF1016_N DUF1133 DUF1153 DUF1323 DUF134 DUF1441 DUF1492 DUF1495 DUF1670 DUF1804 DUF1819 DUF1836 DUF1870 DUF2089 DUF2250 DUF2316 DUF2513 DUF2582 DUF3116 DUF3253 DUF3853 DUF3860 DUF3908 DUF433 DUF4364 DUF4423 DUF4447 DUF480 DUF4817 DUF5635 DUF573 DUF722 DUF739 DUF742 DUF977 E2F_TDP EAP30 eIF-5_eIF-2B ELL ESCRT-II Ets EutK_C Exc F-112 FaeA Fe_dep_repr_C Fe_dep_repress FeoC FokI_C FokI_N Forkhead FtsK_gamma FUR GcrA GerE GntR GP3_package HARE-HTH HemN_C HNF-1_N Homeobox_KN Homeodomain Homez HPD HrcA_DNA-bdg HSF_DNA-bind HTH_1 HTH_10 HTH_11 HTH_12 HTH_13 HTH_15 HTH_16 HTH_17 HTH_18 HTH_19 HTH_20 HTH_21 HTH_22 HTH_23 HTH_24 HTH_25 HTH_26 HTH_27 HTH_28 HTH_29 HTH_3 HTH_30 HTH_31 HTH_32 HTH_33 HTH_34 HTH_35 HTH_36 HTH_37 HTH_38 HTH_39 HTH_40 HTH_41 HTH_42 HTH_43 HTH_45 HTH_46 HTH_47 HTH_48 HTH_49 HTH_5 HTH_50 HTH_51 HTH_52 HTH_53 HTH_54 HTH_55 HTH_56 HTH_57 HTH_6 HTH_7 HTH_8 HTH_9 HTH_ABP1_N HTH_AraC HTH_AsnC-type HTH_CodY HTH_Crp_2 HTH_DeoR HTH_IclR HTH_Mga HTH_micro HTH_OrfB_IS605 HTH_ParB HTH_psq HTH_Tnp_1 HTH_Tnp_1_2 HTH_Tnp_4 HTH_Tnp_IS1 HTH_Tnp_IS630 HTH_Tnp_ISL3 HTH_Tnp_Mu_1 HTH_Tnp_Mu_2 HTH_Tnp_Tc3_1 HTH_Tnp_Tc3_2 HTH_Tnp_Tc5 HTH_WhiA HxlR IBD IF2_N IRF KicB KilA-N Kin17_mid KORA KorB La LacI LexA_DNA_bind Linker_histone LZ_Tnp_IS481 MADF_DNA_bdg MAGE MarR MarR_2 MerR MerR-DNA-bind MerR_1 MerR_2 Mga Mnd1 MogR_DNAbind Mor MotA_activ MqsA_antitoxin MRP-L20 MukE Myb_DNA-bind_2 Myb_DNA-bind_3 Myb_DNA-bind_4 Myb_DNA-bind_5 Myb_DNA-bind_6 Myb_DNA-bind_7 Myb_DNA-binding Neugrin NFRKB_winged NOD2_WH NUMOD1 ORC_WH_C OST-HTH P22_Cro PaaX PadR PapB PAX PCI Penicillinase_R Phage_AlpA Phage_antitermQ Phage_CI_repr Phage_CII Phage_NinH Phage_Nu1 Phage_rep_O Phage_rep_org_N Phage_terminase PheRS_DBD1 PheRS_DBD2 PheRS_DBD3 Pou Pox_D5 PqqD PRC2_HTH_1 PUFD PuR_N Put_DNA-bind_N Raf1_HTH Rap1-DNA-bind Rep_3 RepA_C RepA_N RepC RepL Replic_Relax RFX_DNA_binding Ribosomal_S18 Ribosomal_S19e Ribosomal_S25 Rio2_N RNA_pol_Rpc34 RNA_pol_Rpc82 RNase_H2-Ydr279 ROQ_II RP-C RPA RPA_C RQC Rrf2 RTP RuvB_C S10_plectin SAC3_GANP SANT_DAMP1_like SatD SelB-wing_1 SelB-wing_2 SelB-wing_3 SgrR_N Sigma54_CBD Sigma54_DBD Sigma70_ECF Sigma70_ner Sigma70_r2 Sigma70_r3 Sigma70_r4 Sigma70_r4_2 Ski_Sno SLIDE Slx4 SMC_Nse1 SMC_ScpB SoPB_HTH SpoIIID SRP19 SRP_SPB STN1_2 Sulfolobus_pRN Sun2_CC2 Suv3_N Swi6_N SWIRM Tau95 TBPIP TEA Terminase_5 TetR_N TFA2_Winged_2 TFIIE_alpha TFIIE_beta TFIIF_alpha TFIIF_beta Tn7_Tnp_TnsA_C Tn916-Xis TraI_2_C Trans_reg_C TrfA TrmB tRNA_bind_2 tRNA_bind_3 <