Control region

The control region, which typically has a length of about 1,150 bp, is the only extended non-coding region of the mitogenome. This region is often referred to as ‘D-loop’, although the true D-loop does neither span the entire control region nor is it found in all mtDNA molecules at any given time (Pereira et al., 2008; Nicholls & Minczuk, 2014). 

For descriptive purposes, Brown et al. (1986) first divided the control region into three domains, with a conserved central domain being flanked by highly variable domains on either side. The authors did not, however, define an exact boundary to separate domains 1 and 2 from each other.