BIO1140 CLASS NOTES - TOPIC 11

BIO1140 CLASS NOTES - TOPIC 11 - TOPIC 11 CELL CONNECTIONS...

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TOPIC 11: CELL CONNECTIONS/ CELL JUNCTIONS Three fundamental propositions - tissues are made up of cells and an extracellular matrix - Tissues have a variety of special ways to acquire tensile strength and to communicate with each other - In general we are held together b y innumerable connections between the cytoskeleton of one of our cells with that of most other cells with some connections often involving special transmembrane and extracellular matrix proteins Adhesive Junctions Link cells together into tissues there by causing the cells to function as a unit Anchors the cytoskeleton to the cell surface results in an interconnected network that helps to maintain tissue integrity and withstand stress Two main types of proteins 1. Intracellular Attachment Proteins Form a plaque on the inside of cell membranes which form connection junctional complexes to either intermediate or actin filaments Plaque: intracellular attachment proteins form a fibrous plaque on the cytoplasmic side of the plasma membrane (seen in Desmosomes) 2. Cadherins Protrude on the outer surface of the membrane and bind cells to each other Two main classes of adhesive junctions 1. Adherens Junctions Cell to cell or cell to ECM adhesion Attach via actin filaments Uses cadherins Prominent in heart muscles, epithelial cells (adhesion belt), neuronal synapses 20-25nm space between adjacent membranes They are two types of Adherens junctions Focal adhesions (cell to ECM) - Spot welds cells to matrix - Transmembrane linkers are integrins - Purpose: is to act as a gateway passage for molecules Adhesion belts (cell to cell) - Continuous zones of attachment (around the cell) - Transmembrane linkers are cadherins - Intracellular anchor proteins are talin or filamin
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- Similar to tight junctions but main function is to hold cells together Question: in book it says that talin is used in focal adhesion
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2. Desmosomes Cell to cell Gives the tissue structural integrity causes the cells to work as a unit and resist stress Found in skin, heart muscle, and uterus Transmembrane proteins are cadherins (desmogleins) Desmosome core : extracellular space (25 – 35nm) between the two membranes Desmogleins & Desmocollins:
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This note was uploaded on 06/17/2008 for the course BIO 1140 taught by Professor Fenwick during the Winter '07 term at University of Ottawa.

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BIO1140 CLASS NOTES - TOPIC 11 - TOPIC 11 CELL CONNECTIONS...

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