Sequence and structure comparison of ATP synthase F0 subunits 6 and 8 in notothenioid fish.
The Channichthyidae family (icefish) are the only known vertebrate species to be devoid of haemoglobin. Mitochondrial changes such as tight coupling of the mitochondria have facilitated sustained oxygen and respiratory activity in the fish. This makes it important to appreciate features in the sequence and structure of the proteins directly involved in proton transport, which could have physiological implications. ATP synthase subunit a (ATP6) and subunit 8 (ATP8) are proteins that function as part of the F0 component (proton pump) of the F0F1complex. Both are encoded by the mitochondrial genome and involved in oxidative phosphorylation. To explore mitochondrial sequence variation for ATP6 and ATP8 we have gathered sequences and predicted structures of these two proteins of fish from the Notothenioidei sub-order, a sub-Antarctic species. We compared these with seven other vertebrate species in order to reveal whether there might be physiologically important differences that can help us to understand the unique biology of the icefish.