1 / 26

Cell to Cell Communication

Cell to Cell Communication. Signal Transduction Converting an extracellular signal to an intracellular response Primary Messengers Hormones, neurotransmitters, growth factors, cytokines, prostaglandins, etc. Messenger = Ligand (Binds to receptor with great specificity) Secondary Messengers

quemby-kent
Download Presentation

Cell to Cell Communication

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cell to Cell Communication • Signal Transduction • Converting an extracellular signal to an intracellular response • Primary Messengers • Hormones, neurotransmitters, growth factors, cytokines, prostaglandins, etc. • Messenger = Ligand (Binds to receptor with great specificity) • Secondary Messengers • cAMP, Phosphoinositides, Ca2+

  2. Why Use Hormone Signaling? • General systemic responses • Any cells that possess receptors • Longer acting, slower developing responses • Cause changes in cell growth, differentiation, function • Exert varied responses in different cells/tissues • Cells can have different numbers of receptors or develop different responses with same receptors • Can integrate different messenger inputs • Control inputs can be prioritized (e.g., local control can be modulated or overridden)

  3. Growth Hormone

  4. Control of Chemical Signals • Short-term • Release, uptake and clearance • Longer-term • Up or down regulation of number of receptors (highly variable from ~2,000 to ~100,000)

  5. Extracellular Hormone (H) Membrane Receptor (R) Intracellular [R] + [H]  [RH] [R] [H] KD = [RH] [H] = KD when [R] = [RH]

  6. What does Kd mean? • For insulin, Kd is 2(10-8)M • M= molar = moles/liter = concentration of substance • Insulin has a molecular weight of 5,808 g/mole • Thus, concentration of insulin when half of receptors are bound is equal to 2(10-8)M x 5,808 g/mole = 0.00012 g/l or 0.12 μg/ml • Blood contains ~10,000 μg/ml of total protein • Insulin signaling occurs in the presence of ~100,000 excess protein (background “noise”) • Erythropoietin has a Kd of 10-10M (0.003 μg/ml) • Signaling occurs in the presence of >3,000,000 background

  7. [RH] 1 Then = RT 1+KD / [H] KD [H] And = RT -1 [RH] Let [R] + [RH] = RT

  8. KD Then based on [H] = RT - 1 [RH] Fewer receptors means reduced sensitivity: Suppose - cell has 10,000 receptors - KD = 10 –8 M = 10 nM - 1000 bound receptors generate desired response [H] = 1.1 x 10-9 M With RT = 2000, then [H] = 1.0 x 10-8 M With RT = 1100, then [H] = 1.0 x 10-7 M

More Related