Folding of newly synthesized proteins poses challenges for a functional proteome. Dedicated protein quality control (PQC) systems promote either the folding of nascent polypeptides at ribosomes or, if this fails, ensure their degradation. While well studied for cytosolic protein biogenesis, it is not understood how these processes work for mitochondrially-encoded proteins, key subunits of the oxidative phosphorylation system (OXPHOS). Here, we identify dedicated hubs in proximity to mitoribosomal tunnel exits coordinating mitochondrial translation, protein import, assembly, and protein turnover. Conserved prohibitin/m-AAA protease supercomplexes and the availability of assembly chaperones determine the fate of newly synthesized proteins by molecular triaging. The localization of these competing activities in vicinity to the mitoribosomal tunnel exit allows for a prompt decision whether newly synthesized proteins are fed into OXPHOS assembly or degraded. This repository hosts the whole proteome of PHB1/2 deletion cells and is related to other repositories: