Rat mitochondrial mtDNA-binding proteins to inter-specifically conserved sequences in the displacement loop region of vertebrate mtDNAs.

We describe two new inter-specifically conserved sequences named Mt5 and Mt6 elements which are around the termination associated sequence (TAS) at the 3' end of the displacement loop (D-loop) region of vertebrate mtDNAs. We employed gel mobility shift assay to search for D-loop-binding proteins using partially purified rat mitochondrial mtDNA-binding proteins and 10 human DNA fragments covering the entire D-loop region as probe DNAs. Competition binding assays indicated the presence of four different rat mitochondrial D-loop-binding proteins. Each of the rat proteins bound, in a sequence-specific manner, to a probe DNA containing an inter-specifically conserved sequence; TAS, Mt5, B block, and a A+T-rich sequence overlapping the conserved sequence block I.