Polypeptide Chain Degradation
Polypeptide Chain Degradation - Related Videos
02:11
Proteins: From Genes to Degradation
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2020
Within a biological system, the DNA encodes the RNA, and the nucleotide sequence in the RNA further defines the amino acid sequence in the protein. This is referred to as “The Central Dogma of Molecular Biology” - a term coined by Francis Crick. Central dogma is a firm principle in biology that defines the flow of genetic information within any life form. The two fundamental steps in central dogma are - transcription and translation. Transcription is the synthesis of RNA molecules by RNA...
09:42
Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
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Cited by 6 •
2012
We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.
10:15
Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA
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Cited by 2 •
2012
A technique to identify translational pause sites on mRNA is described. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA, followed by the size analysis of the nascent chains using a denaturing gel electrophoresis.
07:35
Non-chromatographic Purification of Recombinant Elastin-like Polypeptides and their Fusions with Peptides and Proteins from Escherichia coli
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Cited by 48 •
2014
Elastin-like polypeptides are stimulus-responsive biopolymers with applications ranging from recombinant protein purification to drug delivery. This protocol describes the purification and characterization of elastin-like polypeptides and their peptide or protein fusions from Escherichia coli using their lower critical solution temperature phase transition behavior as a simple alternative to chromatography.
07:43
Assaying Proteasomal Degradation in a Cell-free System in Plants
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Cited by 26 •
2014
Targeted protein degradation represents a major regulatory mechanism for cell function. It occurs via a conserved ubiquitin-proteasome pathway, which attaches polyubiquitin chains to the target protein that then serve as molecular “tags” for the 26S proteasome. Here, we describe a simple and reliable cell-free assay for proteasomal degradation of proteins.
FAQs
Proteases catalyze the hydrolysis of peptide bonds, using water to cleave a protein chain into smaller peptides and amino acids. This chemical step converts an intact polypeptide into fragments that the cell can process further. Because the products differ in size and composition, degradation supports both selective protein turnover and the recovery of reusable molecular building blocks.
Ubiquitin tagging marks particular proteins for recognition by the proteasome, rather than allowing indiscriminate breakdown of cellular proteins. This targeting system helps direct damaged, misfolded, or short-lived proteins into a controlled dismantling pathway. Selective recognition is important for protein quality control and cellular regulation because it links a protein’s condition or lifespan to its removal.
The proteasome serves as a cellular system that identifies and dismantles proteins marked by ubiquitin. Its activity converts selected protein substrates into smaller degradation products, supporting the removal of molecules that are damaged, misfolded, or no longer needed. This function connects protein turnover with the maintenance of cellular protein quality and regulated biological activity.
Lysosomes provide another cellular route for degrading proteins, alongside the ubiquitin-proteasome system. The source material distinguishes these pathways by identifying ubiquitin tagging and the proteasome as a selective recognition-and-dismantling system, while lysosomes represent an alternative degradative compartment. Considering both routes gives a broader view of how cells manage protein turnover and recycling.
The resulting peptides and amino acids can be reused for protein synthesis or further metabolized. This makes degradation more than a disposal process: it returns molecular components to cellular use and connects protein turnover with nutrient recycling and metabolism. The eventual fate of these products therefore influences both the availability of building blocks and broader cellular resource management.
Analyzing these pathways helps researchers examine gene regulation, cellular stress responses, disease mechanisms, and changes in protein turnover caused by drugs. Altered degradation can affect which proteins persist and which are removed, making the process relevant to both normal biology and disease-related research. The pathways also provide a framework for interpreting how pharmacological changes influence cellular protein balance.