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Cell Signaling Dr. L
Cell signaling
| Question | Answer |
|---|---|
| What is the agonist? | the primary signal that interacts with some type of receptor system. in some cases it can be the cell |
| What does the receptor signal lead to? | Some chemical cascade of events which leads to a biological response |
| Name some biological responses | contraction, relaxation, secretion, transcription, translation, vision and hearing |
| True or False: Agonist have different effects depending on what cell they are interacting with | True. Ex. smooth muscle: NO relaxes muscle. Platelets, NO inhibits activation |
| Mast cell example | Once activated releases histamine and heparin sulfate that causes vasodilation of smooth muscle cells and in endothelial cells vascular permeability |
| If there is tissue injury what do mast cells do? | Degranulate which increases vasular permeability allowing fluid to get into the underlying tissue. ex. neutrophils |
| True or False: Agonist can be soluble, extracellular matrix associated proteins (collagens) or cell associate cell to cell interactions | True |
| What is a good example of cell to cell interactions | C-kit of stem cells and steel factor of adventia cells |
| Describe autocrine | A molecule that acts as a primary signal and feedsback onto the same cell |
| Describe panacrine | A signal that is released from a cell and interacts with receptors on neighboring target cells |
| Describe endocrine | A product that is being released and uses the vasculature and then binds to a receptor on a target cell |
| What are most receptor cells? | Proteins. they can be glycolipids |
| Do receptors have specificity? | yes, they bind a specific extracellular signal molecule and initiates a response in a cell |
| What is saturability? | When you have a limited number of responses |
| What is signaling ability? | When you induce signal transduction. A receptor is defined as a protein or glycolipid that will bind an external signal |
| Are cell surface receptors hydrophillic? | Yes because it can't get through the lipid bilayer. It binds a plasma membrane receptor and that initiates a signal transduction response |
| Are intracellular receptors hydrophillic? | No they are lipophilic or hydrophobic |
| Name some lipophilic moleucles | Steroids: Cortisol, estradiol, testosterone, thyroxine, Vitamin D |
| What type of factors are the intracellular receptors? | Transcription factors. They tend ot have ligand binding and DNA binding domains |
| Do the receptors exist in an inactive or active conformation? | inactive. The signal binds to the ligand binding pocked and causes conformational change allowing the receptor to interact with DNA binding elements |
| compare effect of acetylcholine in cardiac muscles, skeletal and salivary glands | Cardiac: Decreased rate of contraction. Skeletal: increased contraction. Salivary glands: induced secretion |
| Describe ion-channel linked receptors | Allow ions to come down concentration gradient when opened |
| Describe ligand gated channels | Ligand has to bind to channel and then ions come down conentraion gradient |
| Describe voltage gated channels | Due to depolarization the channel opens up |
| describe mechanical gated channels | Stretch a cell and it could lead to opening |
| What happens in a channel in series? | Depolarization can be propogated down a very long distance. One opening leads to opening of adjacent channel |
| Where is the primary signal from typically? | From the outside of the cell and it can generate a second messenger to move the biological signals forward |
| What is crosstalk? | When you activate one system and that can activate multiple things |
| Name components of a G-protein coupled system | Receptor, coupling protein, and enzyme (in that order) |
| How many transmembranes do G-protein coupled receptors have? | 7 |
| Name the 3 subunits of Heterotrimeric g-proteins | alpha, beta and gamma |
| when GDP comes off of H. G-proteins what stays together out of the subunits? | beta and gamma. and the alpha is free (GTP receptor itself) |
| Describe the adenyl cyclase system | Receptor activate a G protein, alpha activates adenyl cyclase,Takes ATP and makes cyclic AMP, activates Protein Kinase A, cAMP bings to regulatory subunits and frees catalytic subunits |
| Name a couple of residues | Serine, threonines and tyrosines |
| True or False: Kinases put on phosphate and phosphatases remove phosphate | True |
| True or False: Enzymes that can phosphorylate tyrosine can only phosphorylate tyrosine | True |
| Can enzymes that phosphorylate serine also phosphorylate threonine | yes and vice versa |
| When you phosphorylate something do you have to dephosphorylate it? | Yes, turn it on you have to turn it off. Remove the signaling molecule from receptor or desensitize receptor: Endocytosis |
| What does phospholipase C target? | Phophatidylinostiol. It will hydrolyze it leading to the generation of two potent secondary messengers: inostiol trisphophate (IP3) and diacyglycerol |
| What does IP3 bind to? | To receptors on the endoplasmic reticulum that will open up a channel which allows calcium to come out to activate kinases, calmodulin etc. |
| Plug and Play Model | Epinephrine, adrenergic will activate Gs which is specific G-protein that will activate adrenylate cyclase and increases cAMP |
| What do you think of anytime you see a tyrosine kinase? | Growth |
| What does thrombin do in the plug n play model? | comes in and cleaves the whole terminal segment of the receptor which leads to activation of receptor |
| What are the 3 domains of the receptors? | ligand binding, transmembrane and internal catalytic |
| What does tyrosine kinase activate? | Ras which is a monomeric GTP binding protein that lives at the plasma membrane because it has an isoprenylation group. |
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Kahiranoel@gmail.com
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