BIO315H5 Lecture Notes - Lecture 1: Protein Kinase, Enzyme, G Protein–Coupled Receptor
Document Summary
Allows organisms to respond to changes in their environment. A typical intracellular signaling pathway: signal molecule (ligand) binds to receptor, receptor activates protein to initiate signalling cascade, cascade alters activity of effector (target) proteins --> alters behaviour of cell, process is called signal transduction. Receptors tend to bind with high affinity to the ligand. 4 components to cell communication: signal molecules, receptor proteins. Extracellular signal molecules can act over short or long distances: contact-dependent. Can be found in the immune system. Membrane bound ligand molecules communicates with a neighbouring cell - requires direct membrane-membrane contact: paracrine. Ligand is secreted by signalling cell that diffuses a short distance and binds to target cells nearby. Special class of paracrine signalling is autocrine signalling - target cell and signalling cell are the same in this case, found in cancer cells. Diffusion of the signalling molecule is limited for a number of reasons.
