YCF45 protein, usually associated with plastids, is targeted into the mitochondrion of Trypanosoma brucei.

YCF45 belongs to a family of proteins of unknown function usually located in the chloroplast of plants. Its highly conserved homologues were found in the genomes of several Trypanosoma and Leishmania species. HA(3)-tagging of the YCF45 protein with the start codon as annotated in the Gene(DB) revealed its cytosolic localization in the cultured procyclic stage of Trypanosoma brucei. However, when a more upstream located start codon was used in another HA(3)-tagged construct, the resulting protein was targeted to the mitochondrion. We propose that YCF45 was acquired by an ancestral trypanosomatid by horizontal gene transfer and in the absence of a plastid was re-targeted to the mitochondrion.