Structure
Most RTKs are single subunit receptors but some exist as multimeric complexes, e.g., the insulin receptor that forms disulfide-linked dimers in the absence of hormone; moreover, ligand binding to the extracellular domain induces formation of receptor dimers. Each monomer has a single hydrophobic transmembrane-spanning domain composed of 25-38 amino acids, an extracellular N-terminal region, and an intracellular C-terminal region. The extracellular N-terminal region exhibits a variety of conserved elements including immunoglobulin (Ig)-like or epidermal growth factor (EGF)-like domains, fibronectin type III repeats, or cysteine-rich regions that are characteristic for each subfamily of RTKs; these domains contain primarily a ligand-binding site, which binds extracellular ligands, e.g., a particular growth factor or hormone. The intracellular C-terminal region displays the highest level of conservation and comprises catalytic domains responsible for the kinase activity of these receptors, which catalyses receptor autophosphorylation and tyrosine phosphorylation of RTK substrates.
Read more about this topic: Receptor Tyrosine Kinases
Famous quotes containing the word structure:
“Slumism is the pent-up anger of people living on the outside of affluence. Slumism is decay of structure and deterioration of the human spirit. Slumism is a virus which spreads through the body politic. As other “isms,” it breeds disorder and demagoguery and hate.”
—Hubert H. Humphrey (1911–1978)
“Just as a new scientific discovery manifests something that was already latent in the order of nature, and at the same time is logically related to the total structure of the existing science, so the new poem manifests something that was already latent in the order of words.”
—Northrop Frye (b. 1912)
“Each structure and institution here was so primitive that you could at once refer it to its source; but our buildings commonly suggest neither their origin nor their purpose.”
—Henry David Thoreau (1817–1862)