This protein family includes human Ecto-NOX disulfide-thiol exchanger 1/2 (ENOX1/2) and similar animal sequences. ENOX1/2 have been long thought to be growth-related cell surface proteins that catalyse both hydroquinone or NADH oxidation and protein disulfide-thiol interchange []; with the two enzymatic activities oscillating with a period length of 24 minutes and playing a role in control of the ultradian cellular biological clock [, ]. Besides, ENOX proteins have been thought to play roles in cancer, cellular time-keeping, growth, aging and neurodegenerative diseases []. However, a recent study cast doubts on these assignments, reports the fly homologue to be a nuclear factor involved in alternative splicing and clarify the lack of evidence on the association of ENOX1 with myasthenia gravis [].
