Cell Bio - Chapter 15 Cell Communication Receptor proteins...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 15: Cell Communication Receptor proteins - receive and bind signals at the cell surface Intracellular signaling pathways - process the signal inside the cell and distribute it to intracellular targets Effector proteins - intracellular targets that are altered by an activated signaling pathway (Ex: gene regulatory proteins, ion channels, or parts of cytoskeleton) Extracellular Signal Molecules -bind to receptors and initiate response in target cells -act in low concentrations -receptors bind them with high affinity -could be proteins, small peptides, amino acids, nucleotides etc. If receptor proteins inside the target cell, signal molecules: -must be small and hydrophobic to diffuse across the target plasma membrane to intracellular receptor protein in cytosol or nucleus Contact-dependent signaling -cells must be in direct membrane-membrane contact -signal molecules bound to the surface of the signaling cell Paracrine signaling -signal molecules are secreted into extracellular fluid -signal molecules only affect cells in the local environment (local mediators) -signal molecules are taken up by target cells, destroyed by enzymes, or immobilized by extracellular matrix Synaptic signaling -in neurons -chemical signals in form of neurotransmitters -signal molecules can act over long distances -faster than endocrine signaling and more precise -neurotransmitters can achieve high local concentration Endocrine signaling -secrete signal molecules called hormones into the bloodstream -long range signaling mechanism -slower than synaptic signaling b/c relies on diffusion and blood flow -low local concentration of hormones Gap Junctions -allow neighboring cells to share signaling information -narrow water filled channels -communication in both direction
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Epithelial cells require survival signals from basal lamina; they die by apoptosis if they lose contact with it Cell’s response to extracellular signals depends on: 1. receptor proteins 2. intracellular machinery Morphogen -extracellular signal molecule during development -generates a signal concentration gradient -cells adopt different fates in accordance with their position in the gradient Nitric oxide (NO) -signal that diffuses into the target cell to activate intracellular receptors -relaxes smooth muscle in animals -endothelial cells release NO in response to acetylcholine release from vessel wall -smooth muscle cells relax and blood vessel dilates -catalyzed by NO synthase -acts locally b/c of short half life Nuclear Receptors -ligand-activated gene regulatory proteins -serve as both intracellular receptors and effectors -have a DNA-binding domain -ligands are steroid hormones, vitamin D, thyroid hormones etc. -ligand binding alters conformation of receptor protein which leads to the binding of co- activator proteins that stimulates gene transcription Classes of Cell Surface Receptor proteins 1. Ion-channel coupled receptors -mediated by neurotransmitters that open or close ion channels 2. G-protein-coupled receptors
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/11/2010 for the course BIO 320 taught by Professor Staff during the Fall '08 term at University of Texas.

Page1 / 7

Cell Bio - Chapter 15 Cell Communication Receptor proteins...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online