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Principal Investigator: Stephen Graf Brohawn
Organization: UNIVERSITY OF CALIFORNIA BERKELEY
Fiscal Year: 2024
Award: $328,607
Funding agency: National Institute of General Medical Sciences
PROJECT SUMMARY
This project aims to understand the function and regulation of three ion channels that conduct K+ across cell
membranes and belong to the two-pore domain K+ channel family. We will apply cryo-electron microscopy to
determine structures of the channels in different functional states within lipid environments that mimic the
cellular membrane and electrophysiological recordings to characterize their activities in order to derive physical
models for channel gating and modulation. We aim to capture structural snapshots of the different open and
closed conformations for each channel by varying conditions that alter channel function including solution
composition, lipid composition, and presence of small molecules or interacting proteins. The three channels
are members of different branches of the two-pore domain K+ channel family. While they share a common
structural architecture, each channel is regulated by pH in a different way; one is inhibited by protons on both
sides of the membrane, the second is inhibited only by extracellular protons, and the third is both inhibited and
altered in its ionic selectivity by extracellular protons. The underlying molecular mechanisms by which pH is
sensed and converted into a change in channel activity are correspondingly different between the channels.
Each channel is further regulated by a distinct set of factors including signaling lipids, interacting proteins,
solution ion composition, and small molecule drugs. Comparative analyses of the three structurally and
evolutionarily related K+ channels will therefore provide additional insight into their functional properties and
biological roles. Two-pore domain K+ channels mediate cellular electrical signaling by establishing and
maintaining the resting membrane potential and opposing excitability. The channels under study here are
involved in respiratory regulation, cardiac rhythm generation, blood pressure control, central chemoreception,
and systemic pH homeostasis among other processes. Their dysregulation is implicated in cardiac arrythmia,
kidney disease, and hypertension in humans and they are targets of anesthetics, antiarrhythmics, and drugs
under investigation for obstructive sleep apnea. Therefore, in addition to providing fundamental mechanistic
insight into the physical and chemical basis for channel function, this work will serve as a basis for the
development of more potent and specific pharmacological agents targeting ion channels to promote health and
treat disease. Importantly, the technical and methodological advances developed here for structural
characterization of small membrane proteins in lipid environments are expected to be widely applicable and will
facilitate insights across the breadth of biology in which membrane proteins play important roles.
Terms: <Acids><Address><Anesthesia><Anesthesia procedures><Anesthestic Drugs><Anesthetic Agents><Anesthetic Drugs><Anesthetics><Anti-Arrhythmia Agents><Anti-Arrhythmia Drugs><Anti-Arrhythmics><Architecture><Assay><BP control><BP homeostasis><BP management><BP regulation><Binding Sites><Bioassay><Biological><Biological Assay><Biology><Breathing><Bupivacaine><Cardiac><Cardiac Chronotropism><Cell Body><Cell Communication and Signaling><Cell Signaling><Cell membrane><Cells><Cellular Membrane><Chemicals><Combining Site><Communication><Complex><Coupled><Cryo-electron Microscopy><Cryoelectron Microscopy><Cytoplasm><Cytoplasmic Membrane><Development><Diffusion><Disease><Disorder><Drug Targeting><Drugs><Electron Cryomicroscopy><Electrophysiology><Electrophysiology (science)><Endocannabinoids><Endogenous Cannabinoids><Engineering / Architecture><Environment><Esthesia><Family><Feedback><G-Proteins><GTP-Binding Proteins><GTP-Regulatory Proteins><Generations><Genetic Alteration><Genetic Change><Genetic defect><Goals><Guanine Nucleotide Coupling Protein><Guanine Nucleotide Regulatory Proteins><H+ element><Health Promotion><Heart Rate><Hereditary><Human><Hydrogen Ions><Hypertension><Hypokalemia><Hypopotassemia><Inherited><Inositide Phospholipids><Inositol Phosphoglycerides><Inositol Phospholipids><Intracellular Communication and Signaling><Investigation><Ion Channel><Ion Channel Protein><Ion Channel Protein Gene><Ionic Channels><Ions><K channel><Kidney Diseases><Kidney Failure><Kidney Insufficiency><Lipid Binding><Lipids><Mammalia><Mammals><Mediating><Medication><Membrane><Membrane Channels><Membrane Potentials><Membrane Protein Gene><Membrane Proteins><Membrane-Associated Proteins><Methodology><Modeling><Modern Man><Molecular><Molecular Configuration><Molecular Conformation><Molecular Stereochemistry><Mutation><N arachidonoyl 2 hydroxyethylamide><N-arachidonoylethanolamine><Nature><Nephropathy><Nerve Cells><Nerve Unit><Neural Cell><Neurocyte><Neurons><Neurophysiology / Electrophysiology><Obstructive Sleep Apnea><Organ><Organism-Level Process><Organismal Process><Pharmaceutical Preparations><Phosphatidyl Inositol><Phosphatidylinositols><Phosphoinositides><Physiologic><Physiologic Processes><Physiological><Physiological Processes><Plasma Membrane><Play><Potassium Channel><Potassium Ion Channels><Process><Property><Protein Subunits><Proteins><Protons><PtdIns><Pulmonary Hypertension><Reactive Site><Receptor Protein><Receptor Signaling><Regulation><Renal Disease><Renal Failure><Renal Insufficiency><Renal function><Research><Respiratory Aspiration><Respiratory Inspiration><Rest><Resting Potentials><Role><Salutogenesis><Sensation><Side><Signal Transduction><Signal Transduction Systems><Signaling><Sleep Apnea><Sleep Apnea Syndromes><Sleep Hypopnea><Sleep-Disordered Breathing><Stimulus><Structure><Surface Proteins><Syndrome, Sleep Apnea, Obstructive><Testing><Transmembrane Potentials><Vascular Hypertensive Disease><Vascular Hypertensive Disorder><Volatilization><Work><anandamide><arachidonoyl ethanolamide><arachidonoylethanolamide><arachidonylethanolamide><arrhythmic agent><base><bases><biologic><biological signal transduction><blood pressure control><blood pressure homeostasis><blood pressure management><blood pressure regulation><cardiac rhythm><comparative><conformation><conformational><conformational state><conformationally><conformations><cryo-EM><cryoEM><cryogenic electron microscopy><design><designing><developmental><diffused><diffuses><diffusing><diffusions><drug/agent><electrophysiological><extracellular><genome mutation><heart rhythm><high blood pressure><hyperpiesia><hyperpiesis><hypertensive disease><hypertensive disorder><insight><inspiration><kidney disorder><kidney function><lipid bound><member><membrane structure><mutant><nanodisk><neuronal><pH Homeostasis><pharmacologic><physical model><plasmalemma><programs><promoting health><receptor><reconstitute><reconstitution><regulate BP><regulate blood pressure><renal disorder><respiratory><sleep-related breathing disorder><small molecule><social role><targeted agent><therapeutic target><voltage>