![]() ![]() MEK = mitogen-activated protein kinase MAPK = mitogen-activated protein kinase Ras = G-protein specific to this pathway RAF = proto-oncogene serine/threonine kinase Ras/RAF/Mitogen-Activated Protein Kinase Pathway.RTK cross-phosphorylation then leads to the phosphorylation of other proteins that will eventually result in modulation of gene transcription. This process is known as cross-phosphorylation. The dimerized RTKs phosphorylate each other multiple times to result in signal amplification. Remember, kinases specifically act to catalyze the phosphorylation of a target molecule, which in this case is a neighboring RTK. When RTKs are activated by an agonist, they form cross-linked dimers resulting in the activation of the tyrosine kinase by phosphorylation. This RTK subclass is activated by pathogen-derived molecules allowing the body to detect unwanted pathogens early on as well as sense “danger” signals leading to the eventual destruction of those pathogens.This RTK subclass is activated by insulin resulting in expression of glucose transporters and allow cells to accumulate glucose from the blood.This RTK subclass is activated by nerve growth factors, more specifically neurotropins a family of proteins involved with development, survival and function of neurons.These receptors are found in abnormally high levels on the surface of a number of types of cancer cells allowing these cells to multiply excessively. This RTK subclass is activated by epidermal growth factor resulting in cell division that leads to cell growth, proliferation and differentiation.RTKs bind growth factors to signal processes that result in the regulation of cell growth, differentiation and survival through gene transcription. When RTK agonists bind to these receptors, their intrinsic enzymatic activity is stimulated. This class of receptors are also considered enzymes that have intrinsic enzymatic activity.do not have a tyrosine kinase domain, rather act through cytoplasmic tyrosine kinases.These kinases may have a role in cell proliferation, differentiation, apoptosis and even embryonic development. specifically phosphorylate the hydroxyl side chains of serine or threonine amino acid residues.Signal transduction through RTK results in specific phosphorylation of tyrosine residues on target proteins and subsequent increase in gene transcription and regulation of cell growth, differentiation and survival. ![]() ![]() make up the majority of enzyme-linked receptors. ![]() They interact with specific target molecules (peptides) with a phosphorylated tyrosine residue.ģ Main Types of Enzyme-Linked Receptors SH2-domains most commonly play a role in the signal transduction by receptor tyrosine kinase pathways as you will see later on in this section.
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