a Physical interactions of mtHSP70-FLAG upon DNAJA3 (JA3) or GRPEL1 (EL1) knockdown. mtHSP70-FLAG was constitutively expressed, immunoprecipitated and analyzed by Western blotting. NT: non-target. b Quantification of intracellular ATP after glucose (GLU) or galactose (GAL) culture in the absence or presence of 5 μM oligomycin (OLG) for 2 h. Red dots indicate individual data points (n = 3 independent experiments). Data are presented as means ± standard deviation. c Effect of galactose culture and oligomycin treatment on mtHSP70 interactions. Immunoprecipitates of mtHSP70-FLAG were analyzed for the indicated proteins. d Mitochondrial protein solubility in control (Ctrl) and LONP1 patient (bi-allelic p.Tyr565His and p.Glu733Lys variants) fibroblasts. e mtHSP70 interactions in control (Ctrl) and LONP1 patient (Pt) fibroblast cells. mtHSP70-FLAG was expressed in the indicated cells and immunoprecipitated. f Comparison of LONP1WT and CODAS LONP1R721G in rescuing mitochondrial protein aggregation in LONP1 knockdown cells. 143B cells expressing siRNA-resistant LONP1WT and CODAS LONP1R721G were treated with siRNA against LONP1 and analyzed by Triton X-100 extraction. g Comparison of LONP1WT and CODAS LONP1R721G in interacting with mtHSP70. FLAG-tagged LONP1WT and CODAS LONP1R721G were expressed in 143B cells, and FLAG immunoprecipitates were analyzed for the indicated proteins.