Translin: A multifunctional protein involved in nucleic acid metabolism

ABSTRACT

Translin, a highly conserved, DNA/RNA binding protein, is abundantly expressed in brain, testis and in certain malignancies. It was discovered initially in the quest to find proteins that bind to alternating polypurines-polypyrimidines repeats.It has been implicated to have a role in RNA metabolism (tRNA processing, RNAi, RNA transport, etc.), transcription,DNA damage response, etc. Studies from human, mice, drosophila and yeast have revealed that it forms an octameric ring,which is important for its function. Translin is a cytoplasmic protein, but under genotoxic stress, it migrates into thenucleus, binds to the break point hot spots and therefore, thought to be involved in chromosomal translocation events aswell as DNA damage related response. Its structure is known and DNA binding regions, GTP binding region and regionsresponsible for homotypic and heterotypic interaction are known. It forms a ball like structure with open central channel foraccommodating the substrate nucleic acids. Besides this, translin protein binds to 30 and 50 UTR of certain mRNAs andprobably regulates their availability for translation. It is also involved in mRNA transport and cell cycle progression. Itforms a heteromeric complex with translin associated factor-X (TRAX) to form C3PO complex which is involved in RNAsilencing process. Recently, it has been shown that translin is upregulated under starvation conditions in Drosophila and isinvolved in the integration of sleep and metabolic rate of the flies. Earlier studies classified translin as a DNA repair protein;however subsequent studies showed that it is a multifunctional protein. With this background, in this review we havesummarized the translin biochemical activities, cellular function as well as structural properties of this important protein.