Isolation of Contact Sites Between Inner and Outer Mitochondrial Membranes

2017 ◽  
pp. 43-51
Author(s):  
Max Harner
Keyword(s):  
Mitochondrial Membranes ◽  
Contact Sites

Structure of contact sites between the outer and inner mitochondrial membranes investigated by HVEM tomography

1996 ◽  
Vol 54 ◽  
pp. 966-967
Author(s):  
C.A. Mannella ◽  
K.F. Buttle ◽  
K.A. O‘Farrell ◽  
A. Leith ◽  
M. Marko
Keyword(s):  
Liver Mitochondrion ◽  
Adenine Nucleotide ◽  
Protein Complexes ◽  
Mitochondrial Membranes ◽  
Electron Microscopic ◽  
Contact Sites ◽  
Transmission Electron ◽  
Precursor Proteins ◽  
Membrane Contacts ◽  
And Function

Early transmission electron microscopy of plastic-embedded, thin-sectioned mitochondria indicated that there are numerous junctions between the outer and inner membranes of this organelle. More recent studies have suggested that the mitochondrial membrane contacts may be the site of protein complexes engaged in specialized functions, e.g., import of mitochondrial precursor proteins, adenine nucleotide channeling, and even intermembrane signalling. It has been suggested that the intermembrane contacts may be sites of membrane fusion involving non-bilayer lipid domains in the two membranes. However, despite growing interest in the nature and function of intramitochondrial contact sites, little is known about their structure.We are using electron microscopic tomography with the Albany HVEM to determine the internal organization of mitochondria. We have reconstructed a 0.6-μm section through an isolated, plasticembedded rat-liver mitochondrion by combining 123 projections collected by tilting (+/- 70°) around two perpendicular tilt axes. The resulting 3-D image has confirmed the basic inner-membrane organization inferred from lower-resolution reconstructions obtained from single-axis tomography.

scholarly journals Protein import into mitochondria: ATP-dependent protein translocation activity in a submitochondrial fraction enriched in membrane contact sites and specific proteins.

1989 ◽  
Vol 109 (6) ◽  
pp. 2603-2616 ◽  
Author(s):  
L Pon ◽  
T Moll ◽  
D Vestweber ◽  
B Marshallsay ◽  
G Schatz
Keyword(s):  
Protein Import ◽  
Protein Translocation ◽  
Buoyant Density ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Mitochondrial Membranes ◽  
Outer Membranes ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Dependent Protein

To identify the membrane regions through which yeast mitochondria import proteins from the cytoplasm, we have tagged these regions with two different partly translocated precursor proteins. One of these was bound to the mitochondrial surface of ATP-depleted mitochondria and could subsequently be chased into mitochondria upon addition of ATP. The other intermediate was irreversibly stuck across both mitochondrial membranes at protein import sites. Upon subfraction of the mitochondria, both intermediates cofractionated with membrane vesicles whose buoyant density was between that of inner and outer membranes. When these vesicles were prepared from mitochondria containing the chaseable intermediate, they internalized it upon addition of ATP. A non-hydrolyzable ATP analogue was inactive. This vesicle fraction contained closed, right-side-out inner membrane vesicles attached to leaky outer membrane vesicles. The vesicles contained the mitochondrial binding sites for cytoplasmic ribosomes and contained several mitochondrial proteins that were enriched relative to markers of inner or outer membranes. By immunoelectron microscopy, two of these proteins were concentrated at sites where mitochondrial inner and outer membranes are closely apposed. We conclude that these vesicles contain contact sites between the two mitochondrial membranes, that these sites are the entry point for proteins into mitochondria, and that the isolated vesicles are still translocation competent.

Contact sites between the inner and outer mitochondrial membranes in stunned versus hibernating myocardium

1995 ◽  
Vol 4 (3) ◽  
pp. 195-202 ◽  
Author(s):  
A. Bakker ◽  
F. Thone ◽  
M. Borgers ◽  
W. Jacob
Keyword(s):  
Hibernating Myocardium ◽  
Mitochondrial Membranes ◽  
Contact Sites

Identification of a GTP-binding protein in the contact sites between inner and outer mitochondrial membranes

1991 ◽  
Vol 180 (3) ◽  
pp. 1453-1459 ◽  
Author(s):  
Trevor Lithgow ◽  
Mark Timms ◽  
Peter B. Hj ◽  
Nicholas J. Hoogenraad
Keyword(s):  
Binding Protein ◽  
Mitochondrial Membranes ◽  
Gtp Binding Protein ◽  
Contact Sites ◽  
Gtp Binding

scholarly journals ORP5 Transfers Phosphatidylserine To Mitochondria And Regulates Mitochondrial Calcium Uptake At Endoplasmic Reticulum - Mitochondria Contact Sites

2019 ◽  
Author(s):  
Leila Rochin ◽  
Cécile Sauvanet ◽  
Eeva Jääskeläinen ◽  
Audrey Houcine ◽  
Amita Arora ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Calcium Uptake ◽  
Vesicular Transport ◽  
Mitochondrial Calcium ◽  
Mitochondrial Membranes ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Mitochondrial Calcium Uptake

SUMMARYMitochondria are dynamic organelles essential for cell survival whose structural and functional integrity rely on selective and regulated transport of lipids from/to the endoplasmic reticulum (ER) and across the two mitochondrial membranes. As they are not connected by vesicular transport, the exchange of lipids between ER and mitochondria occurs at sites of close organelle apposition called membrane contact sites. However, the mechanisms and proteins involved in these processes are only beginning to emerge. Here, we show that ORP5/8 mediate non-vesicular transport of Phosphatidylserine (PS) from the ER to mitochondria in mammalian cells. We also show that ER-mitochondria contacts where ORP5/8 reside are physically and functionally linked to the MIB/MICOS complexes that bridge the mitochondrial membranes, cooperating with them to facilitate PS transfer from the ER to the mitochondria. Finally, we show that ORP5 but not ORP8, additionally regulates import of calcium to mitochondria and consequently cell senescence.

scholarly journals Phospholipid ebb and flow makes mitochondria go

2020 ◽  
Vol 219 (8) ◽  
Author(s):  
Michelle Grace Acoba ◽  
Nanami Senoo ◽  
Steven M. Claypool
Keyword(s):  
Protein Complexes ◽  
Lipid Transfer ◽  
Phospholipid Biosynthesis ◽  
Mitochondrial Membranes ◽  
Lipid Transfer Proteins ◽  
Physiological Functions ◽  
Contact Sites ◽  
Recent Advances ◽  
Cellular Integrity ◽  
Ebb And Flow

Mitochondria, so much more than just being energy factories, also have the capacity to synthesize macromolecules including phospholipids, particularly cardiolipin (CL) and phosphatidylethanolamine (PE). Phospholipids are vital constituents of mitochondrial membranes, impacting the plethora of functions performed by this organelle. Hence, the orchestrated movement of phospholipids to and from the mitochondrion is essential for cellular integrity. In this review, we capture recent advances in the field of mitochondrial phospholipid biosynthesis and trafficking, highlighting the significance of interorganellar communication, intramitochondrial contact sites, and lipid transfer proteins in maintaining membrane homeostasis. We then discuss the physiological functions of CL and PE, specifically how they associate with protein complexes in mitochondrial membranes to support bioenergetics and maintain mitochondrial architecture.

scholarly journals The distribution of anionic sites on the surfaces of mitochondrial membranes. Visual probing with polycationic ferritin.

1975 ◽  
Vol 65 (3) ◽  
pp. 615-630 ◽  
Author(s):  
C R Hackenbrock ◽  
K J Miller
Keyword(s):  
Outer Membrane ◽  
Mitochondrial Membrane ◽  
High Density ◽  
Intermembrane Space ◽  
Mitochondrial Membranes ◽  
Inner Mitochondrial Membrane ◽  
Anionic Sites ◽  
Contact Sites ◽  
Intact Mitochondrion ◽  
Boundary Membrane

Polycationic ferritin, a multivalent ligand, was used as a visual probe to determine the distribution and density of anionic sites on the surfaces of rat liver mitochondrial membranes. Both the distribution of bound polycationic ferritin and the topography of the outer surface of the inner mitochondrial membrane were studied in depth by utilizing thin sections and critical-point dried, whole mount preparations for transmission electron microscopy and by scanning electron microscopy. Based on its relative affinity for polycationic ferritin, the surface of the inner membrane contains discrete regions of high density and low density anionic sites. Whereas the surface of the cristal membrane contains a low density of anionic sites, the surface of the inner boundary membrane contains patches of high density anionic sites. The high density anionic sites on the inner boundary membrane were found to persist as stable patches and did not dissociate or randomize freely when the membrane was converted osmotically to a spherical configuration. The observations suggest that the inner mitochondrial membrane is composed of two major regions of anionic macromolecular distinction. It is well-known that an intermembrane space exists between the two membranes of the intact mitochondrion; however, a number of contact sites occur between the two membranes. We determined that the outer membrane, partially disrupted by treatment with digitonin, remains attached to the inner membrane at these contact sites as inverted vesicles. Such attached vesicles show that the inner surface of the outer membrane contains anionic sites, but of decreased density, surrounding the contact sites. Thus, the intermembrane space in the intact mitochondrion may be maintained by electronegative surfaces of the two mitochondrial membranes. The distribution of anionic sites on the outer surface of the outer membrane is random. The nature and function of fixed anionic surface charges and membrane contact sites are discussed with regard to recent reports relating to calcium transport, protein assembly into mitochondrial membranes, and membrane fluidity.

scholarly journals Miro clusters regulate ER-mitochondria contact sites and link cristae organization to the mitochondrial transport machinery

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Souvik Modi ◽  
Guillermo López-Doménech ◽  
Elise F. Halff ◽  
Christian Covill-Cooke ◽  
Davor Ivankovic ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Super Resolution ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Localization ◽  
Mitochondrial Membranes ◽  
Mouse Embryonic Fibroblasts ◽  
Contact Site ◽  
Embryonic Fibroblasts ◽  
Contact Sites ◽  
Regulated Trafficking

Abstract Mitochondrial Rho (Miro) GTPases localize to the outer mitochondrial membrane and are essential machinery for the regulated trafficking of mitochondria to defined subcellular locations. However, their sub-mitochondrial localization and relationship with other critical mitochondrial complexes remains poorly understood. Here, using super-resolution fluorescence microscopy, we report that Miro proteins form nanometer-sized clusters along the mitochondrial outer membrane in association with the Mitochondrial Contact Site and Cristae Organizing System (MICOS). Using knockout mouse embryonic fibroblasts we show that Miro1 and Miro2 are required for normal mitochondrial cristae architecture and Endoplasmic Reticulum-Mitochondria Contacts Sites (ERMCS). Further, we show that Miro couples MICOS to TRAK motor protein adaptors to ensure the concerted transport of the two mitochondrial membranes and the correct distribution of cristae on the mitochondrial membrane. The Miro nanoscale organization, association with MICOS complex and regulation of ERMCS reveal new levels of control of the Miro GTPases on mitochondrial functionality.

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