Description: Protects against mitochondrial dysfunction during cellular stress by phosphorylating mitochondrial proteins. Involved in the clearance of damaged mitochondria via selective autophagy (mitophagy) by mediating activation and translocation of PRKN (PubMed:14607334, PubMed:15087508, PubMed:19229105, PubMed:19966284, PubMed:20404107, PubMed:20798600, PubMed:23620051, PubMed:23754282, PubMed:23933751, PubMed:24660806, PubMed:24751536, PubMed:24784582, PubMed:24896179, PubMed:25527291). Targets PRKN to dysfunctional depolarized mitochondria through the phosphorylation of MFN2 (PubMed:23620051). Activates PRKN in 2 steps: (1) by mediating phosphorylation at 'Ser-65' of PRKN and (2) mediating phosphorylation of ubiquitin, converting PRKN to its fully-active form (PubMed:24660806, PubMed:24751536, PubMed:24784582, PubMed:25527291). Required for ubiquinone reduction by mitochondrial complex I by mediating phosphorylation of complex I subunit NDUFA10 (By similarity).