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A protease (also called a peptidase, proteinase, or proteolytic enzyme) [1] is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. [2] They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water ...
Cyclins are a group of proteins that activate kinases involved in cell division. The degradation of cyclins is the key step that governs the exit from mitosis and progress into the next cell cycle. [15] Cyclins accumulate in the course the cell cycle, then abruptly disappear just before the anaphase of mitosis. The cyclins are removed via a ...
Without regulation, proteases will destroy many proteins which are essential to physiological processes. One way the body regulates proteases is through protease inhibitors. Protease inhibitors can be other proteins, small peptides, or molecules. There are two types of protease inhibitors: reversible and irreversible.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
If the substrate is water then hydrolysis results; if it is an organic molecule then that molecule is transferred onto the first substrate. Attack by the second substrate forms a new tetrahedral intermediate, which resolves by ejecting the enzyme's nucleophile, releasing the second product and regenerating free enzyme.
Molecules enter and exit the mitochondrial matrix through transport proteins and ion transporters. Molecules are then able to leave the mitochondria through porin . [ 9 ] These attributed characteristics allow for control over concentrations of ions and metabolites necessary for regulation and determines the rate of ATP production.
The cell cycle is a series of complex, ordered, sequential events that control how a single cell divides into two cells, and involves several different phases. The phases include the G1 and G2 phases, DNA replication or S phase, and the actual process of cell division, mitosis or M phase. [ 1 ]
Proteostasis is the dynamic regulation of a balanced, functional proteome.The proteostasis network includes competing and integrated biological pathways within cells that control the biogenesis, folding, trafficking, and degradation of proteins present within and outside the cell.