Researchers and Instructors
Protein export systems in pro- and eukaryotes direct newly synthesized polypeptides from the cytosol to their site of function. For many proteins, export from the cytosol relies on signalrecognition particle (SRP), an evolutionarily conserved protein that binds newly synthesized polypeptides as they emerge from the ribosome. SRP targets the entire mRNA-ribosome-nascent polypeptide complex to protein transport machinery (a translocase) in the endoplasmic reticulum of eukaryotes or the cytoplasmic membrane in prokaryotes. Studies of the SRP-based targeting mechanism in pro- and eukaryotes indicate that general steps in the targeting reaction are conserved; GTP binding and hydrolysis by SRP and its receptor are used to control SRP binding and release of the targeting substrate. Recent progress indicates that multiple protein interactions enable SRP to communicate with the ribosome, SR, and the translocase, thereby ensuring that targeting substrates are released only in the presence of an available translocase.
However, these interactions and their relationship to guanine nucleotide binding/ hydrolysis by SRP and SR are still poorly understood. My primary focus is the study of a novel posttranslational SRP targeting system in chloroplasts in order to understand specific protein interactions and their role in regulating the SRP/SR GTPase cycle, a cycle difficult to study in co-translational systems due to the presence of the ribosome.
Protein export systems.
Ph.D. University of Arkansas, 2001
V. Sivaraja, T.K.S. Kumar, P.S.T. Leena, A. Chang, C. Vidya, R.L. Goforth, D. Rajalingam, K. Arvind, J. Ye, J. Chou, R. Henry, C. Yu. 2005. Three-dimensional solution structures of the chromodomains of cpSRP43. J. Biol. Chem 280: 41465-41471.
Cai, Y., M. Moore, R.L. Goforth, R. Henry, R. Beitle. 2004. Genomic data for alternate production strategies: Identification of major contaminating species for Co(II) immobilized metal affinity chromatography. Biotechnology and Bioengineering 88 (1): 77-83.
Goforth, R.L., E.C. Peterson, J. Yuan, M.J. Moore, A.D. Kight, M.B. Lohse, J. Sakon, R.L. Henry. 2004. Regulation of the GTPase cycle in posttranslational signal recognition particle based protein targeting involves cpSRP43. J. Biol. Chem. 279: 43077-84.
M. Moore, R.L. Goforth, H Mori, R.A. Henry. 2003. Functional interaction of chloroplast SRP/FtsY with the ALB3 translocase in thylakoids: substrate not required. J Cell. Biol. 162: 1245-54.
R.L. Goforth, A.K. Chi, L.L. Providence, R.E. Koeppe II, O.S. Andersen, D.V. Greathouse, Hydrophobic coupling of lipid bilayer energetics to channel function. 2003. J. Gen Physiol. 121:477-493.