biostudies-literatureUnknownChang YTNINDS NIH HHSNIGMS NIH HHSNIH HHSMost of the mitochondria proteome is nuclear-encoded, synthesized by cytoplasmic ribosomes, and targeted to mitochondria post-translationally. However, a subset of mitochondrial-targeted proteins is imported co-translationally, although the molecular mechanisms governing this process remain unclear. We employ cellular cryo-electron tomography to visualize interactions between cytoplasmic ribosomes and mitochondria in <i>Saccharomyces cerevisiae</i>. We use surface morphometrics tools to identify a subset of ribosomes optimally oriented on mitochondrial membranes for protein import. This allows us to establish the first subtomogram average structure of a cytoplasmic ribosome on the surface of the mitochondria in the native cellular context, which showed three distinct connections with the obioRxiv : the preprint server for biology2024.07.17.604013https://www.ebi.ac.uk/biostudies/studies/S-EPMC11275913biostudies-literatureCytoplasmic ribosomes on mitochondria alter the local membrane environment for protein import.PMC11275913RF1 NS125674R35 GM128798S10 OD032467Rahmani HChang YTGrotjahn DABarad BAZid BMfalseCytoplasmic ribosomes on mitochondria alter the local membrane environment for protein import.Most of the mitochondria proteome is nuclear-encoded, synthesized by cytoplasmic ribosomes, and targeted to mitochondria post-translationally. However, a subset of mitochondrial-targeted proteins is imported co-translationally, although the molecular mechanisms governing this process remain unclear. We employ cellular cryo-electron tomography to visualize interactions between cytoplasmic ribosomes and mitochondria in <i>Saccharomyces cerevisiae</i>. We use surface morphometrics tools to identify a subset of ribosomes optimally oriented on mitochondrial membranes for protein import. This allows us to establish the first subtomogram average structure of a cytoplasmic ribosome on the surface of the mitochondria in the native cellular context, which showed three distinct connections with the o2024-01-01T00:00:00Z2024 Jul2026-04-07T21:19:30.922Z2025-04-04T02:47:49.397ZS-EPMC112759133907131410.1101/2024.07.17.604013