Regulation of intracellular proteins
There are many ways to regulate the function of proteins in cells, as described in detail below.
Allosteric regulation: The type of protein that now undergoes a change in conformation with various ligands (including substrates, inhibitors, activators, etc.), resulting in a change in affinity with subsequent ligands, is collectively referred to as an allosteric protein. The phenomenon that a ligand that previously binds to a protein can alter the affinity of a subsequent ligand that binds to the same protein is called an allosteric effect, and a protein with an allosteric effect is called an allosteric protein. The previously bound ligand in the allosteric effect can increase or decrease the affinity of the subsequent ligand binding to the same protein. According to whether the previous ligand is the same as the subsequent ligand, the synergistic effect and the heterogeneous effect can be separated. None of the prior binding ligands promotes binding of subsequent ligands but also hinders binding of subsequent ligands to proteins. The interaction of the ligand with the protein at least regulates the stage of protein activity without the formation of covalent bonds, and the formation of the product under the catalysis of the protein sometimes forms a covalent bond over a period of time in the course of the reaction. There are very few allosteric proteins that have only one peptide chain, such as glucose-stimulated proteins in the liver.
Covalent regulation: including reversible and irreversible modification, the former has protein phosphorylation, adenylation, etc., the latter mainly refers to the protein is cut off part of the primary structure fragment to form or expose the active center and become an active protein.
Activation/inhibition of protein regulation of proteins and regulation of proteins by proteins. The former, such as calmodulin, can regulate the activity of various proteins, the regulation of the catalytic activity of Cyclin on CDK, etc., the latter, such as punctate protein, when it binds to biofilm, its activity is different from that when it is not bound, that is, the protein is in the cell. The effect of positioning on its activity.
The regulation of the number of proteins: including the difference in the expression of proteins due to the regulation of gene expression, including the degradation of proteins - this is often associated with other biomacromolecules, such as the proteasome.
The compartments of eukaryotic cells also have a significant effect on the spatial localization of proteins and the transport of proteins in cells to the activity of proteins. The transport of proteins in cells requires not only signal peptides or peptides to guide the proper transport and localization of protein proteins in cells, but also transmembrane transport. Under the action of molecular chaperones, protein molecules will be folded when transported across the membrane. Folding, the different folding states of the protein affect the activity of the protein. The various membranous organelles of eukaryotic cells form different subcellular environments, and the activity of the same protein in different subcellular environments will be different.
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2. John E. Burke.; et al. Structural Basis for Regulation of Phosphoinositide Kinases and Their Involvement in Human Disease. Molecular Cell. 2018, 71: 653-673.