InterPro domain: IPR018105

Mammalian translationally controlled tumour protein (TCTP) (or P23) is a protein which has been found to be preferentially synthesised in cells during the early growth phase of some types of tumour [ 1 , 2 ], but which is also expressed in normal cells. The physiological function of TCTP is still not known. It was first identified as a histamine-releasing factor, acting in IgE +-dependent allergic reactions. In addition, TCTP has been shown to bind to tubulin in the cytoskeleton, has a high affinity for calcium, is the binding target for the antimalarial compound artemisinin, and is induced in vitamin D-dependent apoptosis. TCTP production is thought to be controlled at the translational as well as the transcriptional level [ 3 ].

TCTP is a hydrophilic protein of 18 to 20 kD. TCTPs do not share significant sequence similarity with any other class of proteins. Recently, the structure of TCTP was determined and exhibited significant structural similarity to the human protein Mss4, which is a guanine nucleotide-free chaperone of the Rab protein [ 4 ]. Close homologues have been found in plants [ 5 ], earthworm [ 6 ], Caenorhabditis elegans (F52H2.11), Hydra, Saccharomyces cerevisiae (YKL056c) [ 7 ] and Schizosaccharomyces pombe (SpAC1F12.02c).

1. The growth-related protein P23 of the Ehrlich ascites tumor: translational control, cloning and primary structure. Biochem. Int. 19, 277-86
2. Nucleotide sequence of a major messenger RNA for a 21 kilodalton polypeptide that is under translational control in mouse tumor cells. Nucleic Acids Res. 16, 2350
3. Expression of the gene and processed pseudogenes encoding the human and rabbit translationally controlled tumour protein (TCTP). Eur. J. Biochem. 267, 5473-81
4. Structure of TCTP reveals unexpected relationship with guanine nucleotide-free chaperones. Nat. Struct. Biol. 8, 701-4
5. An alfalfa cDNA encodes a protein with homology to translationally controlled human tumor protein. Plant Mol. Biol. 19, 501-3
6. Identification of heavy metal induced changes in the expression patterns of the translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus1. Biochim. Biophys. Acta 1398, 294-304
7. Sequence of a 28.6 kb region of yeast chromosome XI includes the FBA1 and TOA2 genes, an open reading frame (ORF) similar to a translationally controlled tumour protein, one ORF containing motifs also found in plant storage proteins and 13 ORFs with weak or no homology to known proteins. Yeast 10 Suppl A, S63-8