Biochemistry Commons^™

Modulation Of Kras Structure And Dynamics By Kras Ubiquitination And Membrane Depolarization, Vinay Nair

Dissertations & Theses (Open Access)

KRAS, a 21 kDa small GTPase protein, functions as a molecular switch playing a key role in regulating cell proliferation. Dysregulation of KRAS signaling by oncogenic mutations leads to uncontrolled cell proliferation, a hallmark of cancer cells. Attempts to therapeutically target oncogenic KRAS have led to limited success resulting in a need to identify new mechanisms to targeting KRAS. The interaction of KRAS with its regulators, effectors, and the membrane present one such avenue. In this study, we investigated how post-translational covalent and environmental modifications could modulate these interactions of KRAS. Using computational molecular dynamics simulations, nuclear magnetic resonance spectroscopy …

Ionic Mechanism Of Lysosomal Function And Cell Metabolism, Jian Xiong

Dissertations & Theses (Open Access)

Two Pore Channels (TPCs) are endolysosomal ion channels that are permeable to sodium and calcium. Defects in TPCs have been implicated to impair vesicle trafficking, autophagy and cell metabolism control; however, the detailed mechanism remains largely unknown. In this study, I show that TPCs are critical for appropriate cargo delivery to the lysosomes and deletion of either TPC1 or TPC2 leads to delayed clearance of autophagosomes, resulting in enlarged lysosomes and accumulated contents inside the lysosomes. Cells with both TPC deleted also exhibit 50% reduction in lysosomal amino acids under normal culture conditions, leading to reduced homeostatic mTORC1 activation.

Glutamine …

Investigations Of The Structure-Function Relationship In Kainate Receptors Using FöRster Resonance Energy Transfer, Douglas Litwin

Dissertations & Theses (Open Access)

Kainate receptors belong to the family of ion channels known as the ionotropic glutamate receptors. Ionotropic glutamate receptors mediate the majority of excitatory synaptic transmission, modulate the release of presynaptic glutamate, and facilitate dendrite formation. Kainate receptors are unique among the ionotropic glutamate receptors in being modulated by sodium ions. They have also been implicated in the development of higher learning and epilepsy. In recent years a wealth of structural data has become available for the AMPA and NMDA classes; however, the structural characterization of kainate receptors has been limited. The work in this dissertation utilizes luminescence resonance energy transfer …

Nanoscale Organization Of The Small Gtpase Rac1, Kelsey Maxwell

Dissertations & Theses (Open Access)

Rac1 is a small, guanine-nucleotide binding protein that cycles between an inactive GDP-bound and active GTP-bound state to regulate actin-mediated motility, migration, and adhesion. Plasma membrane (PM) localization is essential for its biological activity. Rac1 PM targeting is directed by a C-terminal membrane anchor that encompasses a geranylgeranyl-cysteine-methyl-ester, palmitoyl, and a polybasic domain (PBD) of contiguous lysine and arginine residues. Using high-resolution imaging combined with spatial mapping analysis, I found that Rac1 forms nanoclusters on the PM. Cycling between the GTP- and GDP-bound states, Rac1 forms nanoclusters that are non-overlapping, consequently undergoing guanine nucleotide-dependent spatial segregation. I further found that …

Fret-Based Investigations Of The Structure-Function Relationships In The Nmda Receptor, Drew M. Dolino

Dissertations & Theses (Open Access)

The N-methyl-D-aspartate (NMDA) receptor is one member of a class of proteins known as the ionotropic glutamate receptors. Ionotropic glutamate receptors mediate the majority of excitatory neurotransmission in the central nervous system, with the NMDA receptor standing out among these receptors for its requirement of a co-agonist, its magnesium-block-based coincidence detection, its slow kinetics, its calcium permeability, its allosteric modulation, and its especially important functional roles in synaptic plasticity, excitotoxicity, and more. In recent years, a wealth of structural information has come about describing endpoint structures to high resolution, but such structures are unable to fully resolve the movements …

Conformational Changes In The Extracellular Domain Of Glutamate Receptors, Anu Rambhadran

Dissertations & Theses (Open Access)

The family of membrane protein called glutamate receptors play an important role in the central nervous system in mediating signaling between neurons. Glutamate receptors are involved in the elaborate game that nerve cells play with each other in order to control movement, memory, and learning.

Neurons achieve this communication by rapidly converting electrical signals into chemical signals and then converting them back into electrical signals. To propagate an electrical impulse, neurons in the brain launch bursts of neurotransmitter molecules like glutamate at the junction between neurons, called the synapse. Glutamate receptors are found lodged in the membranes of the post-synaptic …