Lecture+11+-+Receptors+%26+Cell+Signaling+%232 (4)

Lecture+11+-+Receptors+%26+Cell+Signaling+%232 (4) -...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Monday’s Class: RECEPTORS & CELL SIGNALING #2 Chapter 4 Pages: 98-­‐130 Chapter 3 Pages: 90-­‐121 What you should be able to do by the end of today’s lecture •  Understand the chemical classes of signaling factors. •  Discuss how the chemistry of signal factors influences synthesis, transport, and responsiveness at the target cell. •  Compare the main classes of receptors and provide examples of situaWons where the receptors regulate physiological processes. •  Describe the diversity in receptor-­‐enzymes and enzyme-­‐linked receptors, and recognize the importance of protein kinase and protein phosphatases. •  Discuss how G-­‐protein linked receptors induce downstream responses. Types of Cell Signaling INDIRECT SIGNALING Principles of Animal Physiology Figure 4.2, 4.3 Structure of messenger determines signaling mechanism •  Why would hydrophobic messengers be different from hydrophilic messengers? –  Storage? –  SecreWon? –  Transport? –  Receptor? –  Effects? •  Six main classes of chemicals involved in cellular signaling Transport and Effects of Hydrophobic Messengers Synthesis of pepWde hormones Hydrophilic messengers bind to Transmembrane Receptors When messenger binds receptor, the receptor changes shape, communicaWng (transducing) the signal across the membrane Ligand Chemical messenger that can bind to a specific receptor Principles of Animal Physiology Figure 4.7 Ligand – Receptor InteracWons •  Ligand-­‐receptor interacWons are specific •  Only the correctly shaped ligand (natural ligand) can bind to the receptor •  Ligand mimics •  Agonists – acWvate receptors •  Antagonists – block receptors •  Many ligand mimics act as drugs or poisons Principles of Animal Physiology Figure 4.12 Ligand-­‐Receptor Binding •  L + R ↔ L-­‐R à response –  FormaWon of L-­‐R complex causes response –  More free ligand (L) or receptors (R) will increase the response •  Law of mass acWon •  Receptors can become saturated at high L –  Response is maximal Receptor number & affinity can vary •  More receptors = more likely ligand will bind at any given ligand concentraWon •  Can upregulate (e.g. caffeine) and downregulate (e.g. heroin) receptor numbers •  Receptors can vary in the strength with which they bind ligand InacWvaWon of Ligand-­‐Receptor Complex •  L-­‐R complex must be inacWvated to allow responses to changing condiWons Principles of Animal Physiology Figure 4.16 Signal TransducWon Pathways •  Convert signals from one form to another •  Four components –  Receiver: ligand binding receptor –  Transducer: conformaWonal change of the receptor –  Amplifier: the signal transducWon pathway increases the number of molecules affected –  Responder: something that responds to the signal Types of Receptors (hydrophobic vs. philic messengers?) Focus on signal transducWon pathways most important in regulaWng physiological processes Principles of Animal Physiology Figure 4.18 Intracellular Receptors •  Ligand diffuses across cell membrane •  Binds to receptor in cytoplasm or nucleus •  L-­‐R complex binds to specific DNA sequences •  Regulates the transcrip6on of target genes •  increases or decreases producWon of specific mRNA Principles of Animal Physiology Figure 4.19 Changes in gene transcripWon Ligand-­‐Gated Ion Channels Ligand binds to receptor Receptor changes shape opening a channel Ions move across the membrane ConcentraWon and electrical gradients dictate the direcWon of ion movement •  Movement of ions change ion concentraWons which alters the membrane potenWal Principles of Animal Physiology Figure 4.21 •  •  •  •  Receptor Enzymes (also called enzyme/enzyme-­‐linked receptors) •  When acWvated by a ligand the catalyWc domain starts a phosphoryla6on cascade •  Named based on the reacWon catalyzed Principles of Animal Physiology Figure 4.22 G-­‐Protein-­‐Coupled Receptors •  Transmembrane protein that interacts with intracellular G-­‐proteins •  G-­‐proteins – named for their ability to bind guanosine nucleoWdes •  AcWvate second messengers Principles of Animal Physiology Figure 4.27 Cyclic AMP Signaling (First intracellular 2nd messenger discovered) Principles of Animal Physiology Figure 3.27 Next Class: NUTRIENTS & ENERGY METABOLISM Chapter 2 Pages: 39-­‐44, 71-­‐74 Chapter 2 Pages: 22-­‐27, 57-­‐60 ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern