Triiodothyronine (T3) and thyroxine, also known as tetraiodothyronine (T4), play important roles in the regulation of development, growth, and metabolism in humans and other animals. In recent years, increasing evidence has suggested that thyroid hormone‑like compounds are also present in plants. However, their physiological roles and molecular mechanisms of action remain poorly understood.
The aim of this master's thesis was to identify potential T3-binding proteins in the model plant Arabidopsis thaliana. To achieve this, T3 was immobilized on magnetic beads and used in pull down experiments with A. thaliana lysate. Elution fractions obtained by affinity chromatography were analyzed by mass spectrometry, and the identified proteins were functionally classified based on annotations from the UniProt database. In addition, fluorescently labeled T3 was prepared using Alexa Fluor 488 dye, incubated with plant lysate, and the interaction of the labeled hormone with plant proteins was analyzed by native gel electrophoresis.
Mass spectrometry analysis enabled the identification of more than a hundred proteins, among which eight of the most robust candidates were highlighted using a combination of different statistical approaches. These proteins were associated with signaling, membrane-related processes, stress responses, protein homeostasis, and lipid metabolism.
Direct binding of T3 to the identified proteins was not experimentally confirmed within the scope of this study. Nevertheless, the results provide a set of promising candidates for future investigations and represent an important first step toward understanding the possible role of thyroid hormone-like compounds and their potential target proteins in plants.
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