Related Experiment Video
Updated: Jul 16, 2026
08:55
Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae
Published on: July 19, 2021
Yeast mitochondrial division and distribution require the cortical num1 protein
Kara L Cerveny1, Seth L Studer, Robert E Jensen
1Department of Cell Biology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
Developmental Cell
|March 6, 2007
Summary
Num1p, a protein involved in nuclear migration, unexpectedly plays a crucial role in yeast mitochondrial division and inheritance. Num1p interacts with Dnm1p, linking mitochondrial fission and transmission.
Area of Science:
- Cell Biology
- Genetics
Background:
- Mitochondrial division in yeast is essential and primarily mediated by the dynamin-related protein Dnm1.
- The function of Num1p was previously limited to nuclear migration.
Purpose of the Study:
- To investigate novel proteins involved in yeast mitochondrial division.
- To elucidate the role of Num1p in mitochondrial dynamics.
Main Methods:
- High-copy suppressor screening of a dominant-negative Dnm1p mutant.
- Yeast genetics and time-lapse microscopy.
- Analysis of mitochondrial morphology and inheritance in mutant strains.
Main Results:
- Num1p was identified as a novel factor in mitochondrial division and inheritance.
- num1 mutants exhibit reduced mitochondrial fission, forming interconnected tubules similar to dnm1 mutants.
- Num1p localizes to punctate structures, often colocalizing with Dnm1p.
- num1 dnm1 double mutants show defects in mitochondrial inheritance, with mitochondria accumulating in daughter buds.
Conclusions:
- Num1p has an unexpected dual role in both mitochondrial division and inheritance.
- Num1p functions in conjunction with Dnm1p, establishing a link between mitochondrial fission and inheritance.
- This study reveals a new mechanism for mitochondrial transmission in yeast.
Related Concept Videos
01:39Mitochondrial Protein Sorting
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:39Mitochondrial Precursor Proteins
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Most of the mitochondrial precursors...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:37Mitochondria
Mitochondria are eukaryotic cellular organelles that are known to produce energy through a process called oxidative phosphorylation. Besides their primary function, mitochondria are involved in various cellular processes, including cell growth, differentiation, signaling, metabolism, and senescence. Age-related changes cause a decline in mitochondrial quality and integrity due to increased mitochondrial mutations and oxidative damage. Thus, aging can severely impact mitochondrial functions,...
01:37Mitochondria
Mitochondria are eukaryotic cellular organelles that are known to produce energy through a process called oxidative phosphorylation. Besides their primary function, mitochondria are involved in various cellular processes, including cell growth, differentiation, signaling, metabolism, and senescence. Age-related changes cause a decline in mitochondrial quality and integrity due to increased mitochondrial mutations and oxidative damage. Thus, aging can severely impact mitochondrial functions,...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...