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Robert Gundersen - Research

Research in G protein-mediated Signal Transduction using Dictyostelium

Robert E. Gundersen, Ph.D.

Chair & Associate Professor
Department of Molecular & Biomedical Sciences, University of Maine

Guanine nucleotide-binding regulatory protein (G protein) signal transduction in eukaryotes; regulation of chemotaxis, cell differentiation and other cellular responses by G proteins in Dictyostelium discoideum.

In Dictyostelium discoideum, a single G protein a-subunit, Ga2, controls entry into the developmental phase of the cell’s life cycle. Ga2 regulates three different effector systems; guanylyl cyclase, adenylyl cyclase and phospholipase C. How activation of each effector occurs through Ga2 and how this translates into the developmental process is being examined. Present research aims to understand how covalent modification of Ga2 by phosphate, myristate and palmitate regulate Ga2 function.

Currently my lab’s primary focus is to understand  how peripheral membrane proteins cycle on and off of membranes and specifically for Ga2 how membrane cycling fits into the activation-inactivation G protein cycle.   Below are images of cells transformed with Ga2-YFP or with various Ga2 mutations.  The two Ga2 protein mutations that block lipid modifications (G2A, myristoylation and C4A, palmitoylation) as well as the mutation to block Ga2 activation (Q207L) do not localize to the plasma membrane.  In contrast the activating Ga2 mutation ( G208A) still localizes to the plasma membrane as seen in the wild type (WT).


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