Step1: Among 36 Atg gene product, LC3 is the most specific and indispensable molecular marker of autophagy. In the step one, Post-translational modification of LC3: After transcription, LC3-mRNA is translated to Pro form of LC3, which is proteolytically modified to form LC3-I, then this LC3-I is matured by a ubiquitin like conjugation reaction to form a lipidated form of LC3-II.
Step2: In the 2nd Step, Nucleation & Autophagosome formation: A non-lysosomal and unknown origin of isolating membrane (possibly ER) is nucleated with several different Atg proteins including ULK1, Atg5, Atg12, Atg16, Beclin1, LC3-II, etc. After Nucleation, the elegant degradative machinery is processed through expansion of the membrane to form an enclosed double membraned autophagosome. This autophagosome is encircled with different cytoplasmic components and organelles needed to be degraded. The matured LC3-II is found to be attached with the outer and inner membrane of the autophagosome.
Step3: In the 3rd Fusion Step: After autophagosome formation the outer membrane subsequently fuses with lysosome to form a single membraned autolysosome, and in this step, the lysosomal enzyme activates in pH dependent manner for breakdown of cargo carried by autophagosomes.
Step4: Finally Degradation: In this step, degradation is happened by lysosomal degradative enzymes hydralases to release free amino acids to be recycled, essential for cell survival.
Step2: In the 2nd Step, Nucleation & Autophagosome formation: A non-lysosomal and unknown origin of isolating membrane (possibly ER) is nucleated with several different Atg proteins including ULK1, Atg5, Atg12, Atg16, Beclin1, LC3-II, etc. After Nucleation, the elegant degradative machinery is processed through expansion of the membrane to form an enclosed double membraned autophagosome. This autophagosome is encircled with different cytoplasmic components and organelles needed to be degraded. The matured LC3-II is found to be attached with the outer and inner membrane of the autophagosome.
Step3: In the 3rd Fusion Step: After autophagosome formation the outer membrane subsequently fuses with lysosome to form a single membraned autolysosome, and in this step, the lysosomal enzyme activates in pH dependent manner for breakdown of cargo carried by autophagosomes.
Step4: Finally Degradation: In this step, degradation is happened by lysosomal degradative enzymes hydralases to release free amino acids to be recycled, essential for cell survival.