Dimers are connected by a cardiolipin molecule, which has been found to play a key role in stabilization of the holoenzyme complex. The dissociation of subunits VIIa and III in conjunction with the removal of cardiolipin results in total loss of enzyme activity. Subunits encoded in the nuclear genome are known to play a role in enzyme dimerization and stability. Mutations to these subunits eliminate COX function.Assembly is known to occur in at least three distinct rate-determining steps. The products of these steps have been found, though specific subunit compositions have not been determined.Synthesis and assembly of COX subunits I, II, and III are facilitated by translational activators, which interact with the 5’ untranslated regions of mitochondrial mRNA transcripts. Translational activators are encoded in the nucleus. They can operate through either direct or indirect interaction with other components of translation machinery, but exact molecular mechanisms are unclear due to difficulties associated with synthesizing translation machinery in-vitro. Though the interactions between subunits I, II, and III encoded within the mitochondrial genome make a lesser contribution to enzyme stability than interactions between bigenomic subunits, these subunits are more conserved, indicating potential unexplored roles for enzyme activity.
By comparing the luminosity of a color with and without a filter (or between two different filters), the color can be estimated. This is the premise of monocular lenses and the SeeKey. In some US states, achromats can use a red filter while driving to determine the color of a traffic light. To alleviate photophobia stemming from hemeralopia, dark red or plum colored filters as either sunglasses or tinted contacts are very helpful at decreasing light sensitivity. To manage the low visual acuity that is typical of achromatopsia, achromats may use telescopic systems, specifically when driving, to increase the resolution of an object of interest. Epidemiology
Achromatopsia is a relatively uncommon disorder, with a prevalence of 1 in 30,000 people.However, on the small Micronesian atoll of Pingelap, approximately five percent of the atolls 3,000 inhabitants are affected. This is the result of a population bottleneck caused by a typhoon and ensuing famine in the 1770s, which killed all but about twenty islanders, including one who was heterozygous for achromatopsia.The people of this region have termed achromatopsia "maskun", which literally means "not see" in Pingelapese. This unusual population drew neurologist Oliver Sacks to the island for which he wrote his 1997 book, The Island of the Colorblind. Blue cone monochromacy
Blue cone monochromacy (BCM) is another genetic condition causing monochromacy. It mimics many of the symptoms of incomplete achromatopsia and before the discovery of its molecular biological basis was commonly referred to as x-linked achromatopsia, sex-linked achromatopsia or atypical achromatopsia.