IPR035977
Large ribosomal subunit protein bL36 superfamily
InterPro entry
Short name | Ribosomal_bL36_sp |
Overlapping entries |
Description
Ribosomal protein bL36 (also known as L36) is the smallest protein from the large subunit of the prokaryotic ribosome. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities can be grouped into: bacterial L36; algal and plant chloroplast L36; Cyanelle L36; fungal and animal L36. L36 is a small basic and cysteine-rich protein of around 40 amino-acid residues probably involved in late assembly of the 50S particle, in vitro translation and cell growth. This protein shows a zinc-binding CxxC motif. Its paralogue encoded by ykgO (as named in Escherichia coli), lacks the zinc-binding site and replaces RpmJ when zinc availability is low
[1].
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
[4, 3]. 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
[3, 2].
References
1.YkgM and YkgO maintain translation by replacing their paralogs, zinc-binding ribosomal proteins L31 and L36, with identical activities. Ueta M, Wada C, Wada A. Genes Cells 25, 562-581, (2020). PMID: 32559334
2.The end of the beginning: structural studies of ribosomal proteins. Chandra Sanyal S, Liljas A. Curr. Opin. Struct. Biol. 10, 633-6, (2000). View articlePMID: 11114498
3.The ribosome in focus. Maguire BA, Zimmermann RA. Cell 104, 813-6, (2001). View articlePMID: 11290319
4.Atomic structures at last: the ribosome in 2000. Ramakrishnan V, Moore PB. Curr. Opin. Struct. Biol. 11, 144-54, (2001). View articlePMID: 11297922
GO terms
biological process
molecular function
cellular component
Contributing Member Database Entry
- SUPERFAMILY:SSF57840
Representative structure
8b0x: Translating 70S ribosome in the unrotated state (P and E, tRNAs)