TBK1 and amyotrophic lateral sclerosis: In ALS, mutated OPTN and TBK1 accumulate in mitochondria where the ubiquitin-associated (UBA) structural domain of OPTN binds to the ubiquitin chain, promoting mitochondrial phagocytosis after attaching to microtubule associated protein 1A/1B-light chain 3 (LC3).