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Protein degradation is a major regulatory mechanism of gene expression [1] and contributes substantially to shaping mammalian proteomes. [2] Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, but may also occur by intra-molecular ...
The major route for endocytosis in most cells, and the best-understood, is that mediated by the molecule clathrin. [19] [20] This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell. This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell.
Within frogs and fish, however, there exist fundamental differences in how convergent extension is achieved. Frog embryogenesis utilizes cell rearrangement as the sole player of this process. Fish, on the other hand, utilize both cell rearrangement as well as directed migration [1] (Fig. 1) . Cellular rearrangement is the process by which ...
Antigen discrimination by T cell receptors – T cells respond to foreign antigens at low concentrations, while ignoring any self-antigens present at much higher concentration. This ability is known as antigen discrimination. T-cell receptors use kinetic proofreading to discriminate between high and low affinity antigens presented on an MHC ...
Proofreading also occurs in mRNA translation for protein synthesis. [2] In this case, one mechanism is the release of any incorrect aminoacyl-tRNA before peptide bond formation. [3] The extent of proofreading in DNA replication determines the mutation rate, and is different in different species. [4]
Regulation of gene expression by a hormone receptor Diagram showing at which stages in the DNA-mRNA-protein pathway expression can be controlled. Regulation of gene expression, or gene regulation, [1] includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA).
Translation is one of the key energy consumers in cells, hence it is strictly regulated. Numerous mechanisms have evolved that control and regulate translation in eukaryotes as well as prokaryotes. Regulation of translation can impact the global rate of protein synthesis which is closely coupled to the metabolic and proliferative state of a cell.
Biosynthesis occurs due to a series of chemical reactions. For these reactions to take place, the following elements are necessary: [1] Precursor compounds: these compounds are the starting molecules or substrates in a reaction. These may also be viewed as the reactants in a given chemical process.