Biochemistry Commons^™

Proteomic Approaches To Identify Unique And Shared Substrates Among Kinase Family Members, Charles Lincoln Howarth

Dartmouth College Ph.D Dissertations

Protein phosphorylation is a reversible post-translational modification that is a critical component of almost all signaling pathways. Kinases regulate substrate proteins through phosphorylation, and nearly all proteins are phosphorylated to some extent. Crucially, breakdown in phosphorylation signaling is an underlying factor in many diseases, including cancer. Understanding how phosphorylation signaling mediates cellular pathways is crucial for understanding cell biology and human disease.

Targeted protein degradation (TPD) is a strategy to rapidly deplete a protein of interest (POI) and is applicable to any gene that is amenable to CRISPR-Cas9 editing. One TPD approach is the auxin-inducible degron (AID) system, which relies …

Defining The Role Of Tyrosine Phosphorylation In The Regulation Of Connexin43 In Cardiac Diseases, Li Zheng

Theses & Dissertations

Connexins are integral membrane proteins that oligomerize to form gap junction channels. Ions and small molecules diffuse intercellularly through these channels, allowing individual cellular events to synchronize into the functional response of an entire organ. Gap junction channels composed of Connexin43 (Cx43) mediate electrical coupling and impulse propagation in the normal working myocardium. In the failing heart, Cx43 remodeling (decreased expression, altered phosphorylation state, loss at intercalated discs, and increased presence at lateral membranes) contributes to rhythm disturbances and contractile dysfunction. While there is considerable information regarding key interactions of Cx43 in the regulation of gap junction channels, unfortunately, the …

A Novel Switch-Like Function Of Delta-Catenin In Dendrite Development, Ryan Baumert

Dissertations & Theses (Open Access)

The formation of neuronal networks in the brain is tightly regulated, and dependent on the morphology of dendrites, the branch-like signal-receiving structures extending from neurons. Disruptions in dendrite development, or dendritogenesis, can lead to the atypical neuronal connectivity associated with multiple neurodevelopmental diseases. My research addresses molecular processes that underlie dendritogenesis via analysis of a pair of novel interactions involving the protein delta-catenin.

In neurons, delta-catenin localizes to dendrites and synapses, where it functions in their development and maintenance. Structurally, delta-catenin possesses a central Armadillo domain and a C-terminal PDZ-binding motif. This motif associates with PDZ domain-containing proteins, and is …

Phopsphorylation And Ubiquitin Modification At Dna Damage Sites In Response To Double-Strand Breaks, Atanu Paul

Dissertations & Theses (Open Access)

Genomes of all organisms are continuously damaged by numerous exogenous and endogenous sources leading to different kinds of DNA lesions, which if not repaired efficiently may trigger wide-scale genomic instability, a hallmark of cancer development. To overcome this, cells have evolved a sophisticated sensory network called the DNA damage response (DDR) comprised of a large number of distinct protein complexes categorized as sensor, mediator, transducer and effector proteins that amplify the DNA damage signal and activate cell cycle checkpoint to initiate DNA repair or trigger apoptosis where the defect is beyond repair. This intricate signaling pathway is tightly regulated by …

Defining The Role Of Phosphorylation And Dephosphorylation In The Regulation Of Gap Junction Proteins, Hanjun Li

Theses & Dissertations

Gap junctions are intercellular channels that permit the free passage of ions, small metabolites, and signaling molecules between neighboring cells. In the diseased human heart, altered ventricular gap junction organization and connexin expression (i.e., remodeling) are key contributors to rhythm disturbances and contractile dysfunction. Connexin43 (Cx43) is the dominant gap junction protein isoform in the ventricle which is under tight regulation by serine/tyrosine phosphorylation. Phosphorylation and dephosphorylation regulate many aspects of Cx43 function including trafficking, assembly and disassembly, electrical and metabolic coupling at the plaque, as well as to modulate the interaction with other proteins.

Serine phosphorylation has long been …

Phosphorylation Of Histone Deacetylase 6 Within Its C-Terminal Region By Extracellular Signal Regulated Kinase 1, Kendra Allana Williams

USF Tampa Graduate Theses and Dissertations

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The Role Of Argininosuccinate Synthase Serine 328 Phosphorylation In Nitric Oxide Production, Ricci Haines

USF Tampa Graduate Theses and Dissertations

Until recently, the main mechanism of argininosuccinate synthase (AS) regulation was described to exist mainly at the level of transcription. Transcriptional regulation of AS has been shown to be coordinate with eNOS in response to shear stress, hypoxia, tumor necrosis factor á (TNF-á), and PPAR ã agonist troglitizone. However, it is now understood that one level of NO regulation is cellular control of arginine availability to eNOS via post-translational modifications of AS such as phosphorylation. The purpose of this investigation was to determine under what conditions AS is phosphorylated at S328, identify the pathway that AS phosphorylation at S328 plays …

Cdk1 And Plk1 Mediate A Clasp2 Phospho-Switch That Stabilizes Kinetochore–Microtubule Attachments, Ana R. R. Maia, Zaira Garcia, Lilian Kabeche, Marin Barisic

Dartmouth Scholarship

Accurate chromosome segregation during mitosis relies on a dynamic kinetochore (KT)-microtubule (MT) interface that switches from a labile to a stable condition in response to correct MT attachments. This transition is essential to satisfy the spindle-assembly checkpoint (SAC) and couple MT-generated force with chromosome movements, but the underlying regulatory mechanism remains unclear. In this study, we show that during mitosis the MT- and KT-associated protein CLASP2 is progressively and distinctively phosphorylated by Cdk1 and Plk1 kinases, concomitant with the establishment of KT-MT attachments. CLASP2 S1234 was phosphorylated by Cdk1, which primed CLASP2 for association with Plk1. Plk1 recruitment to KTs …

Phosphorylation Of The Glycine Transporter 1, Javier Vargas Medrano

Open Access Theses & Dissertations

The extracellular levels of the neurotransmitter glycine in the brain are tightly regulated by the high-affinity glycine transporter 1 (GlyT1) and the clearance of glycine depends on its rate of transport and the levels of cell surface GlyT1. Over the past years, it has been shown that PKC activation diminishes the activity and promoted phosphorylation of several neurotransmitter transporters including the dopamine, serotonin and norepinephrine transporters however, its role is unknown for the glycine transporter. To get insights into the role of PKC activation on GlyT1 regulation, we used three N-terminus GlyT1 isoforms stably expressed in porcine aortic endothelial (PAE) …

Dictyostelium Myosin-Ie Is A Fast Molecular Motor Involved In Phagocytosis, Ulrike Durrwang, Setsuko Fujita-Becker, Muriel Erent, F. Jon Kull

Dartmouth Scholarship

Class I myosins are single-headed motor proteins, implicated in various motile processes including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Here we describe the cellular localization of myosin-IE and its role in the phagocytic uptake of solid particles and cells. A complete analysis of the kinetic and motor properties of Dictyostelium discoideum myosin-IE was achieved by the use of motor domain constructs with artificial lever arms. Class I myosins belonging to subclass IC like myosin-IE are thought to be tuned for tension maintenance or stress sensing. In contrast to this prediction, our results show myosin-IE to be a fast motor. …