In apoptotic permeabilization of membrane occurs in -

[Medicoman]

In apoptotic permeabilization of membrane occurs in -

1. Nuclear membrane

2. Cytoplasmic membrane

3. Lysosome

4. Ribosome

5. Mitochondrial membrane

Explanation:

• Mitochondrial membrane permeabilization (MMP) is the hallmark of apoptosis.
• The release of proteins from the intermembrane space of mitochondria is one of the pivotal events in the apoptotic process,which can lead to the activation of caspases and the ultimate demise of the cell.
• MMP is regulated by pro and anti-apoptotic members of Bax-Bc12 family of proteins.
• MMP differentially affects the outer and inner mitochondrial membranes :-

1. The inner mitochondrial membrane becomes permeable to solutes upto 1500 Da yet retains matrix proteins in their normal localization.
2. In contrast,the outer mitochondrial membrane, becomes completely permeabilized to proteins , leading to the release of soluble proteins from the mitochondrial intermembrane space to extramitochondrial space.

• Several intermembrane proteins can activate catabolic hydrolases involved in the apoptotic process.
• One such protein is cytochrome-C.
• Cytochrome ‘C’ leaks out from the mitochondria.
• The released cytochrome’ c’ binds to Apaf-1 (apoptosis activating factor-1) in the cytoplasm.
• These complexes aggregate to form apoptosomes.
• The apoptosomes bind to an activate Caspase -9 (initiate caspase).