Elucidating the role of Protein Phosphatase 2A (PP2A) in modulating heterotrimeric G Protein Signaling

Student Classification


Faculty Mentor

Justin Watkins, Ph.D.


Department of Biology

Document Type


Publication Date

Fall 2019




G Proteins are a class of proteins that behave as molecular switches to connect external stimuli with changes in cell physiology and gene expression. Central to this set of proteins is the phosphorylation of REGULATOR OF G PROTEIN SIGNALING 1 (RGS1), an inhibitor of G protein signaling in Arabidopsis thaliana, which leads to its internalization and activation of the G protein pathway. While much progress has been made in discovering the kinases that act on RGS1, very little is known about the phosphatases that reverse this molecular switch. Based on a previous study that examined protein interactions with RGS1 in vitro, we discovered 4 candidate protein phosphatases that may interact with RGS1 to modulate G protein signaling. One of these proteins, ATB α, is a substrate specificity subunit of PROTEIN PHOSPHATASE 2A (PP2A), a heterotrimeric phosphatase with structural, catalytic, and substrate specificity subunits. We predicted that ATB α (PP2A) interacts with RGS1 in planta, modulating G protein activation. We utilized chemiluminescencebased assays to test the interaction between ATB α (PP2A) and RGS1 and to investigate how G protein interactions affect innate plant immunity. Our interaction assay showed a strong interaction between ATB α and RGS1. We also found that atb α null mutant demonstrated a dampened immune response in comparison to WT. Together, these findings confirm the predicted interactions between ATB α and RGS1 in planta, thereby regulating the RGS1-dependent plant immune response.


UNC SPIRE Post-Doctoral Fellow

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