Abstract

Gα12 and Gα13 acquire chemical information from outside the cell and move that information down pathways through guanine nucleotide binding. This pathway is essential for regulating functions including cell growth. Gα12 and Gα13 are proteins located on the cytoplasmic side of the cell membrane that bind guanine nucleotide exchange factors and other targets that regulate processes such as cell differentiation and cytoskeletal remodeling during cell division. Overexpressed Gα12 and Gα13 are implicated in various forms of cancer, including head and neck squamous cell carcinoma, so understanding their roles and regulatory mechanisms is crucial. My project examines the amino acid structure of the protein Gα12, specifically a set of cysteines for which it is not known whether the side chain is targeted for lipid modification. This event, termed palmitoylation, is essential for Gα12 to drive tumorigenic cell growth. Gα12 has a total of three cysteines, with previous research showing that the N-terminal cysteine (Cys-11) is an essential site of palmitoylation, a crucial component to signaling. My project was to engineer mutated variants of Gα12, targeting the other non-N-terminal cysteines to examine their role in tumorigenic signaling.The goal was to better understand the importance of these cysteines with the added benefit of creating mutated forms of Gα12, including a fully isolated N-terminal cysteine and a variant completely devoid of cysteines, to be used in future research. My initial experimental results suggest the cysteines beyond N-terminal Cys-11 are not essential for tumorigenic signaling by Gα12. Because the mechanistic details of Gα12 palmitoylation are yet to be understood, it is important to create these reagents for future experiments in which the palmitoylation state of Gα12 is probed directly.

Keywords

G protein, G12, Palmitoylation

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