Family

Ribosomal protein S2 (IPR001865)

Short name: Ribosomal_S2

Family relationships

Description

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 [PMID: 11297922, PMID: 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 [PMID: 11290319, PMID: 11114498].

Ribosomal S2 proteins have been shown to belong to a family that includes 40S ribosomal subunit 40kDa proteins, putative laminin-binding proteins, NAB-1 protein and 29.3kDa protein from Haloarcula marismortui [PMID: 1531984, PMID: 8119397]. The laminin-receptor proteins are thus predicted to be the eukaryotic homologue of the eubacterial S2 risosomal proteins [PMID: 7899076].

Ribosomal protein S2 (RPS2) are involved in formation of the translation initiation complex, where it might contact the messenger RNA and several components of the ribosome. It has been shown that in Escherichia coli RPS2 is essential for the binding of ribosomal protein S1 to the 30s ribosomal subunit. In humans, most likely in all vertebrates, and perhaps in all metazoans, the protein also functions as the 67 kDa laminin receptor (LAMR1 or 67LR), which is formed from a 37 kDa precursor, and is overexpressed in many tumors. 67LR is a cell surface receptor which interacts with a variety of ligands, laminin-1 and others. It is assumed that the ligand interactions are mediated via the conserved C terminus, which becomes extracellular as the protein undergoes conformational changes which are not well understood. Specifically, a conserved palindromic motif, LMWWML, may participate in the interactions. 67LR plays essential roles in the adhesion of cells to the basement membrane and subsequent signalling events, and has been linked to several diseases. Some evidence also suggests that the precursor of 67LR, 37LRP is also present in the nucleus in animals, where it appears associated with histones [PMID: 18464793, PMID: 18269348, PMID: 18063583, PMID: 9718729, PMID: 10188208, PMID: 18573314, PMID: 15473865, PMID: 3905390, PMID: 6272196, PMID: 1586449, PMID: 10566557, PMID: 12068815, PMID: 12422231, PMID: 17051149].

GO terms

Biological Process

GO:0006412 translation

Molecular Function

GO:0003735 structural constituent of ribosome

Cellular Component

GO:0005622 intracellular
GO:0005840 ribosome

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
CDD
Pfam
PRINTS