BIOL 3510 1st Edition Lecture 20 Outline of Last Lecture I Three Types of Extracellular Receptors II GPCRs Activate G proteins upon Signal Binding III Bacteria exploit G protein activity IV Many actions trigger an increase in intracellular Ca2 concentrations Outline of Current Lecture I Enzyme coupled Receptors II Receptor Tyrosine Kinases III Intracellular Signaling Molecules IV Ras Mutated in Cancerous Cells V Plant Cell Communication Strategies Current Lecture Enzyme coupled receptors Bind signaling molecules extracellularly Often regulate cell growth proliferation differentiation and or survival Receptor tyrosine kinases RTKs 1 2 3 4 Two RTKs dimerize after the signal binding Dimerized rtKs phosphorylate each other Intracellular signaling proteins are activated upon binding to the phosphorylated Rtks Signaling is turned off when protein tyrosine phophatase dephophorylates the RTKs Intracellular signaling molecules activated by the RTKs include 1 Phopholipase C generates DAG and IPs 2 Ras monomeric GTPase attached to the plasma membrane 3 Phosphoinositide 3 kinase Pi 3 kinase phosphorylates inositol phospholipids Ras is activated when a signal binds a RTK leading to the activation of Ras GEF Activated Ras initiates the MAP kinase signaling module Ras is often mutated in cancerous cells These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Mutations affect the GTPase activity of Ras Ras is always on Leads to uncontrolled cell proliferation Pi 3 kinase generates phosphorylated inositol phospholipid upon RTK activation Phosphorylation by Akt indirectly activates tor a kinase which promotes cell growth Plants and animals have different cell communication strategies In plants No RTKs steroid hormone nuclear receptors cAMP and few GPCRs Lots of receptor serine threonine kinases Signal binding to an ethylene receptor relieves transcriptional repression in plants Signaling pathways are highly interconnected Intracellular signaling proteins can integrate incoming signals
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