The characterization of mitochondrial proteins is important for the understanding of both normal cellular function and mitochondrial disease. In the present study we identify a novel mitochondrial protein, PRELI (protein of relevant evolutionary and lymphoid interest), that is encoded within the evolutionarily conserved MAD3/PRELI/RAB24 gene cluster located at chromosome 5q34–q35. Mouse Preli is expressed at high levels in all settings analysed; it is co-expressed with Rab24 from a strong bi-directional promoter, and is regulated independently from the S-phase-specific Mad3 gene located at its 3´ end. PRELI contains a stand-alone 170 amino acid PRELI/MSF1p´ motif at its N-terminus. This domain is found in a variety of proteins from diverse eukaryotes including yeast, Drosophila and mammals, but its function is unknown, and the subcellular location of higher eukaryotic PRELI/MSF1P´ proteins has not been determined previously. We show here that PRELI is located in the mitochondria, and by using green-fluorescent-protein fusion proteins we identify a mitochondrial targeting signal at its N-terminus.
Abbreviations used: AML, acute myeloid leukaemia; bHLH-zip, basic helix–loop–helix leucine zipper; DAPI, 4,6-diamidino-2-phenylindole; FISH, fluorescence in situ hybridization; GFP, green fluorescent protein; LEA, late embryonic abundant; MDS, myelodysplastic syndrome; MEL, mouse erythroleukaemia; neor, coding region of the Tn5 aminoglycoside phosphotransferase neomycin resistance gene; PRELI/Preli, protein of relevant evolutionary and lymphoid interest; RACE, rapid amplification of cDNA ends; UTR, untranslated region.