This presumed domain is found at the N-terminus of La RNA-binding proteins as well as other proteins . The function of this region is uncertain.
Human Ro ribonucleoproteins (RNPs) are composed of one of the four small Y RNAs and at least two proteins, Ro60 and La. The La protein is a 47 kDa polypeptide that frequently acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome [PUBMED:15016896]. In the nucleus, La acts as a RNA polymerase III (RNAP III) transcription factor, while in the cytoplasm, La acts as a translation factor [PUBMED:14636586]. In the nucleus, La binds to the 3'UTR of nascent RNAP III transcripts to assist in folding and maturation [PUBMED:15004549]. In the cytoplasm, La recognises specific classes of mRNAs that contain a 5'-terminal oligopyrimidine (5'TOP) motif known to control protein synthesis [PUBMED:14690589]. The specific recognition is mediated by the N-terminal domain of La, which comprises a La motif and a RNA recognition motif (RRM). The La motif adopts an alpha/beta fold that comprises a winged-helix motif [PUBMED:15048103].