A guanine in the −455 position is important for preferential binding of complex III. In addition to G-455 and A-455 oligonucleotide probes being used in the EMSA analyses, two additional probes with the sequence from −468 to −439 with the following changes, T-455 (thymine in −455 position) and N-455 (no nucleotide in −455 position), were used to determine the effect that the nucleotide in the −455 position has on the binding patterns of the complexes. The radiolabeled probes (A-455, T-455, N-455, and G-455) were competed against all four unlabeled probes at a concentration of 500-fold excess labeled probe. Evident on the 7% nondenaturing gel, complex III was completely competed away in all of these competition assays, except the radiolabeled G-455 competition assay (window no. 4), thus providing more evidence supporting the allelic specficity of complex III to the G-allele.