Summary: Ribosomal L18p/L5e family
Ribosomal L18p/L5e family Provide feedback
This family includes ribosomal proteins from the large subunit. This family includes L18 from bacteria and L5 from eukaryotes. It has been shown that the amino terminal 93 amino acids of P09895 are necessary and sufficient to bind 5S rRNA in vitro . Suggesting that the entire family has a function in rRNA binding.
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This tab holds annotation information from the InterPro database.
InterPro entry IPR005484
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].
This family includes L18 from bacteria and L5 from eukaryotes. The ribosomal 5S RNA is the only known rRNA species to bind a ribosomal protein before its assembly into the ribosomal subunits [PUBMED:8474444]. In eukaryotes, the 5S rRNA molecule binds one protein species, a 34kDa protein which has been implicated in the intracellular transport of 5 S rRNA, while in bacteria it binds two or three different protein species [PUBMED:8219074].
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)|
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This superfamily includes two ribosomal proteins S11 and L18p as well as a domain from eukaryotic peptide chain release factor. This superfamily is likely to share an RNA-binding function.
The clan contains the following 3 members:eRF1_2 Ribosomal_L18p Ribosomal_S11
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
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Curation and family details
|Seed source:||Pfam-B_495 (release 3.0) & Pfam-B_741 (release 4.1)|
|Number in seed:||33|
|Number in full:||5752|
|Average length of the domain:||116.10 aa|
|Average identity of full alignment:||39 %|
|Average coverage of the sequence by the domain:||83.74 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||17|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Ribosomal_L18p domain has been found. There are 229 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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