mTOR
The atypical serine/threonine kinase known as mTOR, which is present in two different complexes, is the target of rapamycin’s molecular action. The first is called mTOR complex 1 (mTORC1) and is suppressed by the drug rapamycin. It is made up of mTOR, Raptor, GL, and DEPTOR. It is a major growth regulator that detects and combines a variety of dietary and environmental stimuli, including growth factors, energy levels, cellular stress, and amino acids. These signals are coupled to the stimulation of cellular growth by phosphorylating substrates that enhance anabolic activities like mRNA translation and lipid synthesis or suppress catabolic processes like autophagy. The tuberous sclerosis heterodimer TSC1/2, the small GTPase Rheb’s GTP-bound state’s GAP, adversely controls the activity of mTORC1 kinase, which is stimulated by the small GTPase Rheb. To control the nucleotide-loading status of Rheb, most upstream inputs are routed through Akt and TSC1/2. On the other hand, amino acids communicate with mTORC1 independently of the PI3K/Akt axis to encourage its movement to the lysosomal surface, where it can be activated in response to Rheb. The coordinated actions of several complexes, particularly the v-ATPase, Ragulator, Rag GTPases, and GATOR1/2, mediate this process. mTOR, Rictor, GL, Sin1, PRR5/Protor-1, and DEPTOR make up the second complex, known as mTOR complex 2 (mTORC2). mTORC2 regulates cytoskeletal dynamics by activating PKC, encourages cellular survival by activating Akt, and promotes ion transport and growth by phosphorylating SGK1. Numerous disease states, such as diabetes, cardiovascular disease, and cancer, are characterized by aberrant mTOR signaling.
mTOR Signaling Pathway
Cell signaling (cell communication in British English) is the capacity of a cell to receive, process, and transmit messages with its surroundings and with itself. Cell signaling is a basic characteristic of all prokaryotic and eukaryotic cellular life. Cell signaling can take place across short or long distances, and is thus classed as autocrine, juxtacrine, paracrine, and endocrine. Signaling molecules can be produced via a variety of biosynthetic pathways and released by passive or active transporters, as well as cell injury.
Receptors are important in cell signaling because they can sense chemical signals as well as physical inputs. Receptors are proteins that are found on the cell surface or within the cell’s interior, such as the cytoplasm, organelles, and nucleus. Additional enzymatic activity such as proteolytic cleavage, phosphorylation, methylation, and ubiquitinylation may occur as a result of these signaling pathways. Each cell is designed to respond to certain extracellular signal molecules, which serve as the foundation for development, tissue repair, immunology, and homeostasis.