Perturbation of the Kynurenine pathway affects the amount of protein-bound 3OH-K.

A-B’: Western blots of protein extracts from heads of flies of different genotypes raised on normal food under physiological/non-degenerative conditions. Blots were tested with antibodies against 3OH-K (A, B) and ß-Tubulin as loading control, run on parallel gels (A’, B’). Numbers on the top of the lanes correspond to the genotypes listed below. Positions of standard molecular weight markers are indicated by arrowheads. Vertical, grey dotted lines outline the lanes. C: A cartoon depicting selected steps of the Kynurenine pathway. Kynurenine 3-monooxygenase (KMO) and Phenoxazinone synthetase (PHS) are enzymes encoded by cinnabar (cn) and cardinal (cd), respectively. White and Scarlet, encoded by white (w) and scarlet (st), respectively, compartmentalize free 3OH-K through their transporter activity into LROs (grey). The schematic represents the emerging hypothesis from the experiments shown in A-B’ that 3OH-K can be bound to proteins (PB-3OH-K) only following its transport into LROs by White and Scarlet.