Cell Communication & Cell Junctions
Integrin, Cell junctions, Gylcoprotein, Quorum Sensing, Signal Trnasduction, Importance of Phosphorylation, Types of Receptors and Ligands, Types of Signalling based on locations
Integrin, Cell junctions, Gylcoprotein, Quorum Sensing, Signal Trnasduction, Importance of Phosphorylation, Types of Receptors and Ligands, Types of Signalling based on locations
Kartei Details
| Karten | 27 |
|---|---|
| Sprache | English |
| Kategorie | Biologie |
| Stufe | Universität |
| Erstellt / Aktualisiert | 04.01.2020 / 12.01.2020 |
| Weblink |
https://card2brain.ch/box/20200104_cell_communication_cell_junctions
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| Einbinden |
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Integrin (location, how does it bind to what)
Cell-membrane anchored protein (transmembrane protein), binds with extracellular matrix (non-covalent and reversible)and with the actin cytoskeleton in the cell
Thight junctions "occluding junctions" (location, function, structure)
Located within the epithelia (between epithelial cells, seal adjacent epithelial cells and prevent molecule and ions to pass, cell membranes are connected by transmembrane proteins (protein strands)
Desmosomes (location, function, structure)
interact with each other in intercellular matrix, act like rivets and keep cells together, keratin fibres (interact with intracellular matrix) and partially embedded proteins
Gap juctions (location, function, structure)
span between to adjacent cell membranes, let water and small dissolved molecule pass ,specialised protein channels (connexins) composed of 5 subunits,
Plasmodesmata (structure, function)
Consists of pores or channels between plant cells, create gaps that connect plant cells, allows molecules and substances to move between adjacent cells, desmotubule (ER that links cells together)
Apical membrane (position, suiting junctions)
Surface of the plasma membrane that faces towards the lumen, tight junctions seal adjacent epithelial cells underneath the apical surface
Basolateral surface (position, suiting junction)
oriented away from the lumen (cell membrane)
Basement membrane (position, suiting junction)$
attached to underlying tissue, ???
Glycoproteins (importance in communication)
specialised for interaction, "sticky" carbohydrate section sticks out the PM to connect to other molecules and is anchored in the PM and able to move around on lipid layer
Quorum (minimum) Sensing (how it works, what is it used for by bacteria)
Glycoproteins in membranes, collectively secrete enzymes, produce antibiotics, bioluminesence
1.Bacteria synthesizes molecules and sectrete into medium
2.Need glycoproteins to interact with ligands (recognition)
3.Response to this interaction
Signal Transduction (main molecules involved, overview of process)
1. Receptor-ligand binding (ligands = molecule with -amine-group -> peptides, sterioids and nucleotides (a lot of hydrophobic regions and carbohydrate groups)
2. Signal transduction (transducer molecule with active and inactive site)
3. Short term cellular responses (increased enzyme activation or cellular movrement)
OR
4. Long term activity -> causes change in DNA transcription
Phosphorylation
Molecules alter from active to inactive (or the opposite) by adding or removing a phosphate group from nucleotides (like ATP or GDP in the cell)
Kinase
Enzyme which adds a phosphate
Phosphatase
Enzyme which removes phosphate
ATP -> ADP
If ATP gives away a phosphate group it becomes ADP
Phosphorylation/Dephosphorylation (active<->inactive)
Some proteins are activated by adding a phosphate group and inactivated by removing a phosphate group. Others are activated by removing the phosphate group and inactivated by adding a phosphate group
Intracellular Receptors
Small or non-polar ligand cross the membrane and interact with receptor in the cytoplasm
Cell-surface receptors
Large and polar ligands can't cross membrane -> bind to transmembrane proteins with a extracellular binding region
3 main sub types of receptors in higher eukaryotes
Ion channel receptors, g-protein coupled receptors, protein kinases
Ion channel receptor
Only opens when a ligand binds to it -> causes conformational change -> enables ions to diffuse through the channel
G-protein coupled receptor (GPCR)
1.GPCR is inactive when g protein is GDP bound
2. Signalling molecule binds to GPCR to activate g-protein
3. G-protein binds to GPCR and nucleotide exchange of swapping GDP with GTP (activates g-protein)
4. Active g-protein binds to inactive enzyme -> causes cellular response
Protein Kinase
Phosphorelation of proteins to activate or deactivate them -> incstructs cell to do work (grow, divide)
Endocrine
Related to glands which secrete hormones or other products directly in the bloodstream
Paracrine
Relating to a hormone which only affect adjactent parts near the gland
Autocrine (signalling)
Relating to a cell-produced substance that only has an effect on the cell by which it is secreted (auto=self)
Signal cell = target cell
Neuronal (signalling)
signalling via neurons to the target cells
Contact-dependent
Target cell is local to target cell
Target cells have fix ligand in membrane which binds to membrane bound receptor of signalling cell
