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Related Concept Videos

Ribosome Profiling02:24

Ribosome Profiling

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Ribosome profiling or ribo-sequencing is a deep sequencing technique that produces a snapshot of active translation in a cell. It selectively sequences the mRNAs protected by ribosomes to get an insight into a cell’s translation landscape at any given point in time.
Applications of ribosome profiling
Ribosome profiling has many applications, including in vivo monitoring of translation inside a particular organ or tissue type and quantifying new protein synthesis levels.
The technique...
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Porin Insertion in the Outer Mitochondrial Membrane01:12

Porin Insertion in the Outer Mitochondrial Membrane

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Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
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Structure of Porins01:21

Structure of Porins

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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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Termination of Translation01:44

Termination of Translation

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The large ribosomal subunit has several important structures essential to translation. These include the peptidyl transferase center (PTC) - which is the site where the peptide bond is formed - and a large, internal, water-filled tube through which the nascent polypeptide moves. This latter structure is called the Peptide Exit Tunnel, and it begins at the PTC and spans the body of the large ribosomal subunit. During translation, as the nascent polypeptide chain is synthesized, it passes through...
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Ribosomal RNA Synthesis02:53

Ribosomal RNA Synthesis

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Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
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Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

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Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
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Updated: Jul 30, 2025

Rapid Isolation of the Mitoribosome from HEK Cells
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Rapid Isolation of the Mitoribosome from HEK Cells

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Insights into mitoribosomal biogenesis from recent structural studies.

Anas Khawaja1, Miriam Cipullo1, Annika Krüger1

  • 1Department of Medical Biochemistry and Biophysics, Division of Molecular Metabolism, Karolinska Institutet, Biomedicum, 171 65 Solna, Sweden; Max Planck Institute Biology of Ageing, Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.

Trends in Biochemical Sciences
|May 11, 2023
PubMed
Summary

Human mitoribosome biogenesis involves assembling mitochondrial RNAs and proteins with assembly factors. Structural insights from cryo-electron microscopy (cryo-EM) detail these processes and their coordination.

Keywords:
assembly factorsmitochondrial ribosomemitoribosome assemblyribosomal RNA

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Last Updated: Jul 30, 2025

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Area of Science:

  • Cell Biology
  • Molecular Biology
  • Structural Biology

Background:

  • The mitochondrial ribosome (mitoribosome) is essential for gene expression within mitochondria.
  • Mitoribosome biogenesis requires the coordinated assembly of mitochondrial and nuclear components.
  • Assembly factors play critical roles in ensuring the correct formation of the mitoribosome.

Purpose of the Study:

  • To review the biogenesis pathways of the mitochondrial small (mtSSU) and large (mtLSU) subunits.
  • To highlight recent structural findings from cryo-electron microscopy (cryo-EM) on mitoribosome assembly factors.
  • To discuss the interplay between mtSSU and mtLSU assembly and mitochondrial gene expression.

Main Methods:

  • Review of recent scientific literature.
  • Analysis of structural data from single-particle cryo-electron microscopy (cryo-EM).
  • Synthesis of findings on mitoribosome assembly pathways.

Main Results:

  • Detailed structural insights into the functions and timing of mitoribosome assembly factors.
  • Characterization of the maturation and folding of mitochondrial RNA components (mt-rRNAs, mt-tRNAVal).
  • Identification of the assembly process involving 82 nucleus-encoded mitoribosomal proteins.

Conclusions:

  • Mitoribosome biogenesis is a complex, multi-step process reliant on numerous assembly factors.
  • Structural studies are crucial for understanding the precise mechanisms of mitoribosome assembly.
  • Further research is needed to elucidate crosstalk between mtSSU and mtLSU assembly and its coordination with mitochondrial gene expression.