Positively regulates mitochondrial complex assembly and/or stability (By similarity). Increases mitochondrial membrane potential while decreasing mitochondrial reactive oxygen species (PubMed:29949756). Increases mitochondrial respiration rate (PubMed:29949756). Increased mitochondrial respiratory activity promotes myogenic differentiation which facilitates muscle growth and regeneration (By similarity). Increases mitochondrial calcium retention capacity (PubMed:29949756). Plays a role in maintenance of cellular lipid composition through its interaction with cytochrome b5 reductase CYB5R3 which is required for mitochondrial respiratory complex I activity (By similarity). Interacts with the mitochondrial trifunctional enzyme complex (MTE) and enhances fatty acid beta-oxidation (PubMed:32243843). Not required for MTE formation or stability (By similarity). Modulates triglyceride clearance in adipocytes through its role in regulating fatty acid beta-oxidation and lipolysis (PubMed:32243843). Interacts with mitochondrial trifunctional enzyme, a heterotetrameric complex composed of 2 HADHA subunits and 2 HADHB subunits (PubMed:32243843). Interacts with cytochrome b5 reductase CYB5R3; the interaction is required to maintain cellular lipid composition and leads to stimulation of mitochondrial respiratory complex I activity (By similarity). Interacts with ATP synthase subunit ATP5F1B/ATP5B (PubMed:32243843). Preferentially binds to cardiolipin relative to other common cell membrane lipids. Levels increase throughout adipogenesis. Belongs to the mitoregulin family.