Dissertation
Insights into the Kinetics and Thermodynamics of Human Aquaporin-4 Orthogonal Array of Particle Assembly in Biomimetic Membranes Using Superresolution Imaging and Single Protein Tracking
Washington State University
Doctor of Philosophy (PhD), Washington State University
2023
DOI:
https://doi.org/10.7273/000005301
Abstract
Aquaporin-4 (AQP4) is a water channel protein primarily located in the plasma membrane of astrocytes in the central nervous system (CNS) and helps to regulate water-ion homeostasis. AQP4 exists in two main isoforms, M1 and M23, which differ in structure by only 23 amino acid residues on the N terminus. The M23 isoform stabilizes itself into protein aggregates known as orthogonal arrays of particles (OAPs), while the M1 isoform does not. The M1 isoform is more mobile and diffuses freely within the plasma membrane. The M1 isoform also has two solvent-accessible cysteine residues on its N-terminal tail that the M23 isoform does not have, which are available to be palmitoylated. Palmitoylation is the enzymatic post-translational process of attaching a palmitic acid lipid group to a cysteine residue via a thioester linkage. Using super-resolution techniques, including stimulated emission depletion (STED) and total internal reflection (TIRF) microscopy, the protein-protein interactions between M1-M1, M1-M23, and M23-M23 are probed. This work also discusses how the palmitoylation state of the M1 isoform changes these protein-protein interactions. From this study, the thermodynamic parameters: Gibbs free energy, Enthalpy, and Entropy are discussed for each of these protein-protein interactions, as well as fundamental statistical mechanical models describing the protein binding behavior. Furthermore, these fundamental findings will be compared to protein aggregates observed in live cell systems and describe how the protein interactions observed in the model system are comparable to those observed in nature.
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Details
- Title
- Insights into the Kinetics and Thermodynamics of Human Aquaporin-4 Orthogonal Array of Particle Assembly in Biomimetic Membranes Using Superresolution Imaging and Single Protein Tracking
- Creators
- Jessica Dileen Carder
- Contributors
- James A. Brozik (Advisor)Xiaofeng Guo (Committee Member)Kerry W Hipps (Committee Member)Ursula Mazur (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemistry, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 187
- Identifiers
- 99901031340301842
- Language
- English
- Resource Type
- Dissertation