Tyrosine kinase receptors consist of a tyrosine kinase domain, domain, and a carboxy-terminal segment with multiple tyrosines for auto The activation of signalling by tyrosine kinase receptors involves Ligand-induced oligomerisation of the receptor, Trans-phosphorylation of the activation loop; Phosphorylation of additional sites and recruitment of proteins to the receptor Phosphorylation of substrates. Tyrosine kinase receptor family, which includes epithelial growth factors fibroblast growth factors and insulin-like growth factors; Cytokine receptor superfamily; Serine-threonine kinase receptor family; Phosphotyrosine phosphatase family Seven transmembrane domain receptors, associated with GTP-activated protein(G-protein)-coupled receptors e Four transmembrane domain receptors, that form ligand -or transmitter gated ion channels Intercellular junctions Types of intercellular junctions Adherent junctions, which hold epithelial cells, as well as cardiac muscle cells, together. This is achieved by connecting cytoskeletal elements of the Tight (occluding) junctions, which segregate the apical and basolateral domains of the cell membrane by sealing the lateral intercellular junctions They prevent pericellular diffusion of water and ions, thereby performing a barrier function Gap(communicating) junctions, which allow intercellular diffusion of ions and signalling molecules. These are composed of hexagonal arrays of identical and tightly packed connexins or gap junction channel proteins, each of which connexon. Gap junctions permit electrical coupling between cellf ey form a shows a central pore of an approximate diameter of 1.5 nm. theTyrosine kinase receptor family, which includes epithelial growth factors, fibroblast growth factors and insulin-like growth factors; Cytokine receptor superfamily; Serine-threonine kinase receptor family; Guanyl cyclase receptor family; Phosphotyrosine phosphatase family. * Seven transmembrane domain receptors, associated with GTP-activated protein (G-protein)-coupled receptors. * Four transmembrane domain receptors, that form ligand- or transmitter￾gated ion channels. & Intercellular junctions Types of intercellular junctions * Adherent junctions, which hold epithelial cells, as well as cardiac muscle cells, together. This is achieved by connecting cytoskeletal elements of the cells. * Tight (occluding) junctions, which segregate the apical and basolateral domains of the cell membrane by sealing the lateral intercellular junctions. They prevent pericellular diffusion of water and ions, thereby performing a barrier function. * Gap (communicating) junctions, which allow intercellular diffusion of ions and signalling molecules. These are composed of hexagonal arrays of identical and tightly packed connexins or gap junction channel proteins, each of which shows a central pore of an approximate diameter of 1.5 nm. They form a connexon. Gap junctions permit electrical coupling between cells. Tyrosine kinase receptors consist of a tyrosine kinase domain, a hormone-binding domain, and a carboxy-terminal segment with multiple tyrosines for auto￾phosphorylation. The activation of signalling by tyrosine kinase receptors involves: Ligand-induced oligomerisation of the receptor; Trans-phosphorylation of the activation loop; Phosphorylation of additional sites and recruitment of proteins to the receptor complex; Phosphorylation of substrates. Cell physiology 4