879-904 cell signaling (2)

879-904 cell signaling (2) - MECHANICS OF CELL...

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MECHANICS OF CELL COMMUNICATION Intro GENERAL PRINCIPLES OF CELL COMMUNICATION Extracellular Signal Molecules Bind to specific receptors o Receptors are transmembrane proteins on the target cell surface Extracellular signal molecules can act over either short or long distances o Some signal molecules stay bound to surface of signaling cell and influence only the shit that comes into contact with it, these are called contact-dependent signaling o Contact-dependent signaling is important for development and immune responses o Signal molecules can act as local mediators o Paracrine signaling – secreted molecules carried far to act on other cells o Autocrine signaling – acts on itself o Secreted protein antagonists affect the distance over which a paracrine signal protein acts o The antagonists bind either to the signal molecule or its cell-surface receptor and block its activity o You can signal over long distances using either neurons or endocrine cells o Endocrine cells secrete their signal molecules called hormones into the bloodstream Gap junctions allow neighboring cells to share signaling information o Gap junctions allow exchange of inorganic ions and small water soluble molecules but NOT macromolecules or nucleic acids Each cell is programmed to respond to specific combinations of extracellular signal molecules o Many epithelial cells require survival signals from the basal lamina on which they sit o They die by apoptosis if they lose contact with this sheet of matrix Different types of cells usually respond differently to the same extracellular signal
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879-904 cell signaling (2) - MECHANICS OF CELL...

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