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In prokaryotes, the term corepressor is used to denote the activating ligand of a repressor protein. For example, the E. coli tryptophan repressor (TrpR) is only able to bind to DNA and repress transcription of the trp operon when its corepressor tryptophan is bound to it.
Repressible systems - A repressible system is on except in the presence of some molecule (called a corepressor) that suppresses gene expression. The molecule is said to "repress expression". The manner by which this happens is dependent on the control mechanisms as well as differences between prokaryotic and eukaryotic cells.
The protein kinase domain is a structurally conserved protein domain containing the catalytic function of protein kinases. [2] [3] [4] Protein kinases are a group of enzymes that move a phosphate group onto proteins, in a process called phosphorylation. This functions as an on/off switch for many cellular processes, including metabolism ...
An adaptive enzyme or inducible enzyme is an enzyme that is expressed only under conditions in which it is clearly of adaptive value, as opposed to a constitutive enzyme which is produced all the time. [1] [2] The inducible enzyme is used for the breaking-down of things in the cell.
The L-arabinose operon houses genes coding for arabinose-digesting enzymes. These function to break down arabinose as an alternative source for energy when glucose is low or absent. [ 4 ] The operon consists of a regulatory repressor gene (araC), three control sites (ara02, ara01, araI1, and araI2), two promoters (Parac/ParaBAD) and three ...
Structure of the trp operon. The trp operon is a group of genes that are transcribed together, encoding the enzymes that produce the amino acid tryptophan in bacteria. The trp operon was first characterized in Escherichia coli, and it has since been discovered in many other bacteria. [1]
This includes the functions of histone remodeling enzymes, transcription factors, enhancers and repressors, and many other complexes Productive elongation of the RNA transcript. Once polymerase is bound to a promoter, it requires another set of factors to allow it to escape the promoter complex and begin successfully transcribing RNA.
After being produced, the stability and distribution of the different transcripts is regulated (post-transcriptional regulation) by means of RNA binding protein (RBP) that control the various steps and rates controlling events such as alternative splicing, nuclear degradation (), processing, nuclear export (three alternative pathways), sequestration in P-bodies for storage or degradation and ...