Intrinsic apoptosis
Encyclopedia
Apoptosis
is a programmed form of cell death involving the degradation of cellular constituents by a group of cysteine proteases called caspase
s. The caspases can be activated through either the intrinsic (mitochondrial mediated) or extrinsic (death receptor mediated) apoptotic pathways.
The intrinsic apoptotic pathway is characterized by permeabilisation of the mitochondria and release of cytochrome c
into the cytoplasm
. Cytochrome c then forms a multi-protein complex known as the ‘apoptosome
’ and initiates activation of the caspase cascade through caspase 9.
The extrinsic apoptotic pathway is activated by death receptors on the plasma membrane such as
tumour necrosis factor receptor 1 (TNFR1) and Fas
/CD95. As ligand
s bind to these receptors, the death inducing signaling complex (DISC) is formed leading to initiation of the caspase cascade through caspase 8.
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
is a programmed form of cell death involving the degradation of cellular constituents by a group of cysteine proteases called caspase
Caspase
Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis , necrosis, and inflammation....
s. The caspases can be activated through either the intrinsic (mitochondrial mediated) or extrinsic (death receptor mediated) apoptotic pathways.
The intrinsic apoptotic pathway is characterized by permeabilisation of the mitochondria and release of cytochrome c
Cytochrome c
The Cytochrome complex, or cyt c is a small heme protein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins. Cytochrome c is a highly soluble protein, unlike other cytochromes, with a solubility of about 100 g/L and is an...
into the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
. Cytochrome c then forms a multi-protein complex known as the ‘apoptosome
Apoptosome
The apoptosome is a large quaternary protein structure formed in the process of apoptosis. Its formation is triggered by the release of cytochrome c from the mitochondria in response to an internal or external cell death stimulus...
’ and initiates activation of the caspase cascade through caspase 9.
The extrinsic apoptotic pathway is activated by death receptors on the plasma membrane such as
tumour necrosis factor receptor 1 (TNFR1) and Fas
Fas
Fas can mean the following:* Fas receptor, an important cell surface receptor protein of the TNF receptor family known also as CD95, that induces apoptosis on binding Fas ligand.* Fes, Morocco, the third largest city in Morocco, as an alternate spelling...
/CD95. As ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
s bind to these receptors, the death inducing signaling complex (DISC) is formed leading to initiation of the caspase cascade through caspase 8.