Jones, Alan M.

Kenan Distinguished Professor Emeritus and Research Professor

alan_jones@unc.edu
312 Coker Hall
(919) 962-6932 (office)

We are interested in cell-to-cell communication. At present, our efforts are focused on signaling that depends on the heterotrimeric G protein complex. Much of our work is devoted to understanding novel mechanisms for activating this pathway therefore we are looking at organisms quite divergent to animal cells where much is already understood about G protein signaling. Using the diversity of life to discover the diversity of cell signaling is a powerful approach.

The JonesLab showed that most eukaryotic cells outside of the animal group have a very different mechanism for activation mechanism. Whereas, the rate-limiting step for G protein activation is nucleotide exchange on the Galpha subunit of the complex, in plant cells and protists, this step is spontaneous. Therefore, the need for a G protein coupled receptor to catalyze this GTP for GDP nucleotide exchange is not needed in plant cells and protists. We showed that the reaction that returns G protein activation (GTP-bound) to the inactive state is the rate-limiting step and is mediated by a receptor like protein that accelerates this “off” reaction. However, this is not the only mechanism to control the pool size of the activated G protein. The JonesLab takes a wide variety of experimental and theoretical approaches to solve central basic problems in cell biology with the intent that our work will translate into improved quality of life, create sustainable agriculture, and make us better stewards of the Earth. Mathematical modelers, biochemists, microscopists, physiologists, geneticists are welcomed to join the JonesLab team. Please see the available positions by clicking the link above.

(A) G protein regulation in mammalian cells. In the absence of ligand, G protein forms an inactive heterotrimer with GΒγ dimer (left bottom). Ligand-bound GPCR promotes GDP dissociation and GTP binding on G protein (Top). GTP-bound GΒ dissociates from GΒγ dimer, and both activated GΒ and freely-released GΒγ modulate activity of the effectors (right bottom). GΒ hydrolyses GTP to GDP, and re-binds to GΒγ to return to its inactive state. (B) G protein regulation modeled in Arabidopsis. Arabidopsis G protein (AtGPA1) can spontaneously dissociate GDP and activate itself (left bottom). AtGPA1 does not hydrolyze its GDP rapidly, however AtRGS1, a 7TM-RGS protein, promotes the GTP hydrolysis of AtGPA1 (top). D-glucose or other stimuli functions on AtRGS1 directly or indirectly, and decouples AtGPA1 from AtRGS1 (right bottom). Once released from AtRGS1, AtGPA1 does not hydrolyze its GTP efficiently, maintaining its active state, and modulating the effector activities.