Two forms of cytochrome b in yeast mitochondria: purification, characterization, and localization in the inner mitochondrial membrane

Biochemistry ◽  
1981 ◽  
Vol 20 (26) ◽  
pp. 7557-7565 ◽  
Author(s):  
Yu Shiaw Chen ◽  
Diana S. Beattie
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Membrane ◽  
Yeast Mitochondria ◽  
Inner Mitochondrial Membrane

scholarly journals Hypoxia-inducible gene domain 1 proteins in yeast mitochondria protect against proton leak through complex IV

2019 ◽  
Vol 294 (46) ◽  
pp. 17669-17677 ◽  
Author(s):  
Ngoc H. Hoang ◽  
Vera Strogolova ◽  
Jaramys J. Mosley ◽  
Rosemary A. Stuart ◽  
Jonathan Hosler
Keyword(s):  
Mitochondrial Membrane ◽  
Model Organism ◽  
Proton Pumping ◽  
Integral Membrane Proteins ◽  
Complex Iii ◽  
Proton Leak ◽  
Yeast Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Complex Iv ◽  
Inducible Gene

Hypoxia-inducible gene domain 1 (HIGD1) proteins are small integral membrane proteins, conserved from bacteria to humans, that associate with oxidative phosphorylation supercomplexes. Using yeast as a model organism, we have shown previously that its two HIGD1 proteins, Rcf1 and Rcf2, are required for the generation and maintenance of a normal membrane potential (ΔΨ) across the inner mitochondrial membrane (IMM). We postulated that the lower ΔΨ observed in the absence of the HIGD1 proteins may be due to decreased proton pumping by complex IV (CIV) or enhanced leak of protons across the IMM. Here we measured the ΔΨ generated by complex III (CIII) to discriminate between these possibilities. First, we found that the decreased ΔΨ observed in the absence of the HIGD1 proteins cannot be due to decreased proton pumping by CIV because CIII, operating alone, also exhibited a decreased ΔΨ when HIGD1 proteins were absent. Because CIII can neither lower its pumping stoichiometry nor transfer protons completely across the IMM, this result indicates that HIGD1 protein ablation enhances proton leak across the IMM. Second, we demonstrate that this proton leak occurs through CIV because ΔΨ generation by CIII is restored when CIV is removed from the cell. Third, the proton leak appeared to take place through an inactive population of CIV that accumulates when HIGD1 proteins are absent. We conclude that HIGD1 proteins in yeast prevent CIV inactivation, likely by preventing the loss of lipids bound within the Cox3 protein of CIV.

scholarly journals The Cbp3–Cbp6 complex coordinates cytochrome b synthesis with bc1 complex assembly in yeast mitochondria

2012 ◽  
Vol 199 (1) ◽  
pp. 137-150 ◽  
Author(s):  
Steffi Gruschke ◽  
Katharina Römpler ◽  
Markus Hildenbeutel ◽  
Kirsten Kehrein ◽  
Inge Kühl ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Membrane ◽  
Feedback Loop ◽  
Dual Function ◽  
Bc1 Complex ◽  
Efficient Synthesis ◽  
Inner Mitochondrial Membrane ◽  
Respiratory Chain Complexes ◽  
Complex Assembly ◽  
Chain Complexes

Respiratory chain complexes in mitochondria are assembled from subunits derived from two genetic systems. For example, the bc1 complex consists of nine nuclear encoded subunits and the mitochondrially encoded subunit cytochrome b. We recently showed that the Cbp3–Cbp6 complex has a dual function for biogenesis of cytochrome b: it is both required for efficient synthesis of cytochrome b and for protection of the newly synthesized protein from proteolysis. Here, we report that Cbp3–Cbp6 also coordinates cytochrome b synthesis with bc1 complex assembly. We show that newly synthesized cytochrome b assembled through a series of four assembly intermediates. Blocking assembly at early and intermediate steps resulted in sequestration of Cbp3–Cbp6 in a cytochrome b–containing complex, thereby making Cbp3–Cbp6 unavailable for cytochrome b synthesis and thus reducing overall cytochrome b levels. This feedback loop regulates protein synthesis at the inner mitochondrial membrane by directly monitoring the efficiency of bc1 complex assembly.

Modulation of the calcium-activated BK-channel of the inner mitochondrial membrane by hypoxia

2007 ◽  
Vol 34 (S 2) ◽  
Author(s):  
D Siemen ◽  
Y Cheng ◽  
X Gu ◽  
P Bednarczyk ◽  
GG Haddad ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Bk Channel ◽  
Inner Mitochondrial Membrane

The Efects of Spaceflight on Mitochondria in Human Lymphocytes (Jurkat).

1999 ◽  
Vol 5 (S2) ◽  
pp. 1118-1119
Author(s):  
Heide Schatten ◽  
Marian Lewis
Keyword(s):  
Mitochondrial Membrane ◽  
Space Shuttle ◽  
Human Lymphocytes ◽  
Jurkat Cells ◽  
Apoptotic Bodies ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Alterations ◽  
Mitochondrial Volume ◽  
Number Of Cells ◽  
Related Increase

Spaceflight induced mitochondrial alterations have been reported for muscle and may be associated with altered physiological functions in space. Mitochondrial alterations are also indicative of preapoptotic events which are seen in greater amounts in cells exposed to spaceflight when compared with cells cultured at 1 g. Preapoptotic mitochondrial changes include alterations of processes at the inner mitochondrial membrane and can result in changes in mitochondrial volume. Higher amounts of oxidative stress during space flight may be one of the causes for changes which lead to apoptosis. Jurkat cells flown on the STS-76 space shuttle mission showed an increase in the number of cells with apoptotic bodies early in the mission and a time-dependent, microgravity-related increase in the Fas/APO-1 cell death factor. Here we investigated the morphology of mitochondria in Jurkat cells exposed to spaceflight during the STS-76 mission.

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