La domain explained

Symbol:	La
La domain
Pfam:	PF05383
Interpro:	IPR006630
Smart:	TSPN
Prosite:	PDOC00280
Merops:	I75
Scop:	2mpr
Tcdb:	1.B.3
Cdd:	cd07323

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]

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

Notes and References

1. Izumi RE, Das S, Barat B, Raychaudhuri S, Dasgupta A . 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 . 7 . 3763–76 . April 2004 . 15016896 . 371053 . 10.1128/jvi.78.7.3763-3776.2004.
2. Intine RV, Tenenbaum SA, Sakulich AL, Keene JD, Maraia RJ . Differential phosphorylation and subcellular localization of La RNPs associated with precursor tRNAs and translation-related mRNAs . Mol. Cell . 12 . 5 . 1301–7 . November 2003 . 14636586 . 10.1016/S1097-2765(03)00429-5. free .
3. Alfano C, Sanfelice D, Babon J, Kelly G, Jacks A, Curry S, Conte MR . Structural analysis of cooperative RNA binding by the La motif and central RRM domain of human La protein . Nat. Struct. Mol. Biol. . 11 . 4 . 323–9 . April 2004 . 15004549 . 10.1038/nsmb747 . 24034320 .
4. Keene JD . Posttranscriptional generation of macromolecular complexes . Mol. Cell . 12 . 6 . 1347–9 . December 2003 . 14690589 . 10.1016/S1097-2765(03)00496-9. free .
5. Kenan DJ, Keene JD . La gets its wings . Nat. Struct. Mol. Biol. . 11 . 4 . 303–5 . April 2004 . 15048103 . 10.1038/nsmb0404-303 . 8623162 .
6. Lin-Marq N, Clarkson SG . A yeast RNA binding protein that resembles the human autoantigen La . J. Mol. Biol. . 245 . 2 . 81–5 . January 1995 . 7799435 . 10.1006/jmbi.1994.0008 .