A fish-specific member of the TPPP protein family?

A eukaryotic protein family, the tubulin polymerization promoting proteins (TPPPs), has recently been identified. It has been termed after its first member, TPPP/p25 or TPPP1, which exhibits microtubule-stabilizing function and plays a role in neurodegenerative diseases. In mammalian genomes, two further paralogues, TPPP2 and TPPP3, can be found. In this article, I show that TPPP1 and TPPP3, but not TPPP2, are included in paralogons, on human chromosomes, Hsa5 and Hsa16, respectively. I suggest that the single non-vertebrate tppp gene was duplicated in the first round of whole-genome duplication in the vertebrate lineage giving rise to tppp1 and the precursor of tppp2/tppp3. The existence of a teleost fish-specific fourth paralogue, tppp4, has also been raised, but it is not supported by synteny analysis. Alternatively, the new group can be considered as the fish orthologue of TPPP2. The case that the new group is the consequence of the teleost fish-specific whole-genome duplication (3R) cannot be excluded.