This is the C-terminal domain of Tab2 from plant and cyanobacteria. Tab2 was first identified in Chlamydomonas reinhardtii as a RNA binding protein required for translation of the chloroplast PsaB photosystem I subunit [1]. Later, the Tab2 homologue from Arabidopsis (Atab2) was found involved in the signalling pathway of light-controlled synthesis of photosystem proteins during early plant development, presumably functioning as an activator of translation with targets at PSI and PSII [2,3]. Directed mutagenesis experiments carried out in Chlamydomonas reinhardtii, Tab2 Swiss:Q7X8Y6, indicated the importance of a highly conserved C-terminal tripeptide WLL for normal psaB translation [1].

1: Tab2 is a novel conserved RNA binding protein required for translation of the chloroplast psaB mRNA. Dauvillee D, Stampacchia O, Girard-Bascou J, Rochaix JD; EMBO J. 2003;22:6378-6388. PMID:14633996

2: Large-scale genetic analysis of chloroplast biogenesis in maize. Belcher S, Williams-Carrier R, Stiffler N, Barkan A; Biochim Biophys Acta. 2015;1847:1004-1016. PMID:25725436

3: ATAB2 is a novel factor in the signalling pathway of light-controlled synthesis of photosystem proteins. Barneche F, Winter V, Crevecoeur M, Rochaix JD; EMBO J. 2006;25:5907-5918. PMID:17139246