La domain

In molecular biology, the La domain is a conserved protein domain. Human 60 kDa SS-A/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 Sjögren syndrome.^[1] In the nucleus, La acts as a RNA polymerase III (RNAP III) transcription factor, while in the cytoplasm, La acts as a translation factor.^[2] In the nucleus, La binds to the 3'UTR of nascent RNAP III transcripts to assist in folding and maturation.^[3] In the cytoplasm, La recognises specific classes of mRNAs that contain a 5'-terminal oligopyrimidine (5'TOP) motif known to control protein synthesis.^[4] The specific recognition is mediated by the N-terminal domain of La, which comprises a La motif and an RNA recognition motif (RRM). The La motif adopts an alpha/beta fold that comprises a winged-helix motif.^[5]

La domain
solution structure of the la domain of c-mpl binding protein
Identifiers
Symbol	La
Pfam	PF05383
InterPro	IPR006630
SMART	TSPN
PROSITE	PDOC00280
MEROPS	I75
SCOP2	2mpr / SCOPe / SUPFAM
TCDB	1.B.3
CDD	cd07323
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Homologous La domain-containing proteins have been identified in a wide range of organisms except Archaea, bacteria and viruses.^[6]