Intermembrane space
Encyclopedia
Inner membrane
The inner membrane is the biological membrane of an organelle or Gram-negative bacteria that is within an outer membrane....
and the outer membrane
Outer membrane
The bacterial outer membrane is found in Gram-negative bacteria. Its composition is distinct from that of the cytoplasmic membrane - among other things, the outer leaflet of the membrane includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and it is linked to the cell's...
of a mitochondrion
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
or a chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
. The main function of the intermembrane space is oxidative phosphorylation
Phosphorylation
Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....
.
Channel protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s called porin
Porin (protein)
Porins are beta barrel proteins that cross a cellular membrane and act as a pore through which molecules can diffuse. Unlike other membrane transport proteins, porins are large enough to allow passive diffusion, i.e., they act as channels that are specific to different types of molecules...
s in the outer membrane
Outer membrane
The bacterial outer membrane is found in Gram-negative bacteria. Its composition is distinct from that of the cytoplasmic membrane - among other things, the outer leaflet of the membrane includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and it is linked to the cell's...
allow free movement of ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s and small molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s into the intermembrane space. This doesn't mean that it is essentially continuous with the cytosol
Cytosol
The cytosol or intracellular fluid is the liquid found inside cells, that is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into compartments....
in terms of the solutes
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
relevant for the functioning of these organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
s. Enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s destined for the mitochondrial matrix
Mitochondrial matrix
In the mitochondrion, the matrix contains soluble enzymes that catalyze the oxidation of pyruvate and other small organic molecules.The mitochondrial matrix also contains the mitochondria's DNA and ribosomes. The word "matrix" stems from the fact that this space is viscous, compared to the...
or the stroma
Stroma (animal tissue)
In animal tissue, stroma refers to the connective, supportive framework of a biological cell, tissue, or organ.The stroma in animal tissue is contrasted with the parenchyma.Examples include:* Stroma of iris...
can pass through the intermembrane space via transport through [1]s. These are known as translocase
Translocase
Translocase is a general term for an enzyme that assists in moving another molecule, usually across a membrane.Translocases are most common secretion system in Gram positive bacteria.Examples include:...
of the outer mitochondria membrane (TOM
Translocase of the outer membrane
The translocase of the outer membrane is a complex of proteins found in the outer mitochondrial membrane of the mitochondria. Its function is to allow movement of proteins through this barrier and into the intermembrane space of the mitochondrion. Most of the proteins needed for mitochondrial...
) and translocase
Translocase
Translocase is a general term for an enzyme that assists in moving another molecule, usually across a membrane.Translocases are most common secretion system in Gram positive bacteria.Examples include:...
of the inner mitochondrial membrane (TIM
Translocase of the inner membrane
The translocase of the inner membrane is a complex of proteins found in the inner mitochondrial membrane of the mitochondria. Components of the TIM complex facilitate the translocation of proteins across the inner membrane and into the matrix...
) in mitochondria
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
and translocase
Translocase
Translocase is a general term for an enzyme that assists in moving another molecule, usually across a membrane.Translocases are most common secretion system in Gram positive bacteria.Examples include:...
of the outer chloroplast membrane (TOC) and translocase
Translocase
Translocase is a general term for an enzyme that assists in moving another molecule, usually across a membrane.Translocases are most common secretion system in Gram positive bacteria.Examples include:...
of the inner chloroplast membrane (TIC) in chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s. It tends to have a low pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
because of the proton gradient which results when proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s are pumped from the mitochondrial matrix
Mitochondrial matrix
In the mitochondrion, the matrix contains soluble enzymes that catalyze the oxidation of pyruvate and other small organic molecules.The mitochondrial matrix also contains the mitochondria's DNA and ribosomes. The word "matrix" stems from the fact that this space is viscous, compared to the...
into the intermembrane space during electron transport. The structures responsible for this are coenzyme Q
Coenzyme Q
Coenzyme Q10, also known as ubiquinone, ubidecarenone, coenzyme Q, and abbreviated at times to CoQ10 , CoQ, Q10, or Q, is a 1,4-benzoquinone, where Q refers to the quinone chemical group, and 10 refers to the number of isoprenyl chemical subunits in its tail.This oil-soluble, vitamin-like substance...
, NADH coenzyme Q oxidoreductase
Oxidoreductase
In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another...
complex (complex I), succinate-coenzyme Q oxidoreductase
Oxidoreductase
In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another...
complex (complex II), and coenzyme Q-cytochrome
Cytochrome
Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....
c oxidoreductase
Oxidoreductase
In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another...
complex (complex III).
Intermembrane space of mitochondria
Because of channels in the outer membrane
Outer membrane
The bacterial outer membrane is found in Gram-negative bacteria. Its composition is distinct from that of the cytoplasmic membrane - among other things, the outer leaflet of the membrane includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and it is linked to the cell's...
of the mitochondria, the content of the intermembrane space is similar to that of the content of the cytoplasm.
ATP consists of adenosine — composed of an adenine ring and a ribose sugar — and three phosphate groups (triphosphate)
Intermembrane space of chloroplast
The intermembrane space of the chloroplastChloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
is extremely small, somewhere from 10-20 nm thick.