TPPP orthologs are ciliary proteins

Tubulin polymerization promoting protein, (TPPP/p25), was identified as a brain-specific protein. The potential function of this protein resembled that of MAPs. It is mainly expressed in oligodendrocytes; however, immunopositivity was also detected in glial and neuronal inclusions in synucleinopathies. Here, we show that TPPP gene(s) are conserved in the genomes of ciliated organisms, but are lacking from the nonciliated ones. This recognition is based upon homologous gene sequence analysis, in silico comparative genomic studies, bioinformatic search and experimental evidence. Cilia (flagella) are microtubule-based cellular extensions of sensory and/or motile function. TPPP orthologs are among the only 16 genes that can be found in all ciliated organisms, suggesting that TPPP orthologs may be associated with a basic function of cilia.