InterPro domain: IPR002344

The La protein is a 47kDa polypeptide that often acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome patients [ 1 ]. It occurs in both the nucleus and the cytoplasm, where it takes on different roles [ 2 ]. In the nucleus, La facilitates the production of tRNAs, acting as a RNA polymerase III (RNAP III) transcription factor by binding to the U-rich 3'UTR of nascent transcripts, assisting in their folding and maturation [ 3 ]. In the cytoplasm, La facilitates the translation of specific mRNAs, acting as a translation factor. As a RNA binding protein (RBP), La associates with subsets of mRNAs that contain a 5'-terminal oligopyrimidine (5'TOP) motif known to control protein synthesis. The binding of La to specific classes of RNA molecules regulates their downstream processing, protects them from endonuclease digestion, and organises their export from the nucleus [ 4 , 5 , 6 , 7 ].

1. A peptide from autoantigen La blocks poliovirus and hepatitis C virus cap-independent translation and reveals a single tyrosine critical for La RNA binding and translation stimulation. J. Virol. 78, 3763-76
2. Differential phosphorylation and subcellular localization of La RNPs associated with precursor tRNAs and translation-related mRNAs. Mol. Cell 12, 1301-7
3. Structural analysis of cooperative RNA binding by the La motif and central RRM domain of human La protein. Nat. Struct. Mol. Biol. 11, 323-9
4. Posttranscriptional generation of macromolecular complexes. Mol. Cell 12, 1347-9
5. Eukaryotic mRNPs may represent posttranscriptional operons. Mol. Cell 9, 1161-7
6. Organizing mRNA export. Nat. Genet. 33, 111-2
7. Ribonucleoprotein infrastructure regulating the flow of genetic information between the genome and the proteome. Proc. Natl. Acad. Sci. U.S.A. 98, 7018-24