Center Aligned Text
Welcome to the Home Page for the
Laboratory for the Investigation
Systems of Import
the Theg Lab
at the
College of Biological Sciences
Department of Plant Biology
University of California at Davis

What we do
Who we are
Where we are
Lab news
Who we were
Positions open

Canvas site
PLoS one
Zoom login

Or click the
picture to go
directly to
Steve's useful links

Important Lab Safety Information

link to (M)SDS database
link to SafetyNet 13,, Guidelines for Chemical Spill Control
link to Department of Plant Biology Safety page, with links from there to
    Illness and Injury Prevention Program
    Emergency Action Plan
    Ergonomic Safety

link to UCD Laboratory Safety Manual, in which you will find the Chemical Hygiene Plan

Theg Lab

What goes on in the Theg lab?


The current objectives of the research in the Theg lab are to understand the events surrounding the transport of proteins across biological membranes and their assembly into larger multimeric complexes. Most of the laboratory's efforts focus on protein trafficking and assembly in chloroplasts isolated from higher plants (often peas, but also Arabidopsis, N. benthamiana, and the moss Physcomitrella patens).

These organelles represent an excellent model system in which to study cellular protein targeting as they are easily separated from other organelles, and retain a high level of metabolic activity after isolation. In addition, they contain a level of structural complexity that requires additional sorting of proteins within the organelle. In these sorting reactions, chloroplasts utilize different protein targeting paradigms which are individually used by other organelles. Consequently, lessons learned from the study of protein targeting to and within chloroplasts can, in principle, be applied to a number of other polypeptide translocating systems.

Recently, we have added E. coli to the systems in which we study protein translocation.

We have also made forays into the mechanism of thylakoid division and the biochemistry of stromule formation.

E coli

Who are we?

The group picture above was taken sometime ago. A generally more current view of the lab make-up is given below.

And then in no particular order...

Steve Theg
Well, he's the PI

Reece Riddle
Post-Doctoral Researcher

Vinh Tran
Undergraduate Researcher

Jessica Petty
Undergraduate Researcher

Tyler Chan
Undergraduate Researcher

Monica Tsai
Undergraduate Researcher

Vijayashree Ramamurthy Gayathri
Undergraduate Researcher

Bohan (Valentina) Li
Undergraduate Researcher

Keshita Gaddam
Undergraduate Researcher

Surya Balamurugan
Undergraduate Researcher

Robby Nykodym
Undergraduate Researcher

Christian Reynolds
Undergraduate Researcher

Sarah Stear
Undergraduate Researcher

Diya Suresh
Undergraduate Researcher

Nikhitha Ravi
Undergraduate Researcher

Lauryn Chinn
Dishwashing and such

Andrea Keys
Entropy Reduction Specialist

Katherine Hand
She's actually a member of the Shabek lab, but performs a lot of chloroplast import experiments in the Theg lab.
So, honorary member of the Theg lab

Terry Bricker
Emeritus Professor from Louisiana State University, fiercest member of the lab
(look for his other picture in the lab photo gallery)

  Additional lab photos can be seen here in the lab photo gallery.      

Where are we?

The labs are located in rooms 2105 and 2111 in Green Hall on the UC-Davis campus.

Some of our publications

Click the picture


Click here to see cover images we submitted with our papers (most were rejected)

News from the lab

Click the picture

Former Lab Members (many pictures are from when they were in the lab, they may look older now)

• William F. Ettinger - Postdoc from 1989 to 1992, worked on the assembly of the photosynthetic oxygen-evolving complex. He is currently a Professor at Gonzaga University and Chair of the Biology Department.

Sidney Varian Scott - Graduate Student from 1989 to 1993. Thesis title: The Mechanism of Protein Transport Across the Chloroplast Envelope Membranes.

• Sonya A. Clark - Postdoc from 1993 to 1996, worked on the transport of proteins across the envelope and thylakoid membranes. She was a Principal Scientist at Complete Genomics before we lost track of her.

• Robin A. Roffey - Postdoc from 1993 to 1996, worked on the assembly of the photosynthetic oxygen-evolvng complex. She is currently a Professor in the Department of Biological Sciences at Sacramento City College.


• Akiko Hashimoto - Visiting Graduate Student from 1993 to 1996. During the three years she spent in the Theg lab, she was a registered student at Okayama University, which remained the degree granting institution. Thesis title: Assembly of the Photosynthetic Oxygen-Evolving Complex Subunits from Higher Plants: Site of Assembly and Mechanism of Binding.


• Ellen A. Leheny - Graduate Student from 1991 to 1996. Thesis title: An Investigation of the Conservation of Protein Transport Pathways in Chloroplasts. She is now Director, Melanoma Business Analytics and Insights Lead at Pfizer in New York City.

• Sarah A. Teter - Graduate Student from 1993 to 1997. Thesis title: Electrophysiological and Mechanistic Characterization of a Post-translational Protein Transport Machinery: The Thylakoid Delta pH-Dependent Pathway. She is currently a Project Director at Novozymes.


• Yuka Tomokawa - Visiting Graduate Student from July 1998 to February 1999. She returned to Japan to finish her Master's degree with Professor Yasusi Yamamoto at Okayama University.

• Siegfried Musser - Postdoc from 1997 to August 1999. Worked on the mechanism of protein transport on the thylakoid deltapH-dependent pathway. He is now a Professor at Texas A&M University.

• Mark Havrilla Ainsworth - Graduate student from 1995-2000.Thesis title: Delta-pH Dependant Thylakoid Protein Translocation. Mark is the Biotechnology Program Coordinator/Instructor at Seattle Central Community College. Click on his picture to learn more.

• Heather Scott - Graduate student from 1998 to 2000. After a stint as a Peace Corps volunteer in Mauritania, in western Afirca, she taught high school in New York City. She is now living in Ithica, N.Y. Click on her picture to learn more...

• Nancy Pergam Alder- Graduate Student from 1998-2002. You can learn more about her by clicking on her picture

• Nathan Alder - Graduate Student from 1998-2002. Thesis title: Analysis of the Energentics and Kinetics of Protein Transport via the Delta-pH Dependent/cpTAT Pathway in Thylakoids. Nathan is currently an Associate Professor in the Department of Molecular and Cellular Biology, University of Connecticut. Click on his picture to go to his lab's webpage.


• Nancy Hoffman - Plant Biology Graduate Student from 2000-2005. Thesis title: Protein Targeting in Chloroplasts. She is currently a Science Editor at The Plant Cell.

• Nikolai Braun - Biophysics Graduate Student from 2002-2007. Thesis title: Energetic Studies of the cpTat Protein Transport Pathway.

• Mathias Labs - Visiting Masters Student from Dresden Technical University, March - September 2011. Thesis title: A Folded Protein can be Imported into Chloroplasts.

• Shari Lo - Plant Biology Graduate Student from 2006-2012. Thesis title: Role of Vesicle-Inducing Protein in Plastids 1 in cpTat Transport at the Thylakoid.

• Terry Bricker - Sabbatical Visiting Professor from Louisiana State University during the 2011/2012 academic year. Terry retired to the foothills in Shingle Springs, and is a regular in the lab now.

• Laurie Frankel - Sabbatical Visiting Researcher from Louisiana State University during the 2011/2012 academic year. Laurie retired with Terry to Shigle Springs.

• Lily Liu - Postdoctoral Researcher from 2011-2014. She is currently a Professor at the Kunming Institute of Botany at the Chinese Academy of Sciences.

• Lan-Xin Shi - Project Scientist from 2003-2014. She is currently a scientist with the California Department of Pesticide Regulation.

• Xiaochun Wang - Sabbatical Visiting Professor from Henan Agricultural University during 2014.

• Jonathan Ho - Biophysics Graduate Student from 2010 - 2016. Thesis title: The Dynamic Morphology of the Chloroplast Organelle and Its Effects on Biological Processes He is currently a researcher at LakeParma.

• Ralph McNeilage - BMCDB Graduate Student from 2010- 2016. Thesis title: Protein Import into Chloroplasts

• Philip Day - Plant Biology Graduate Student from 2014 - 2019. Philip was a student with Kentaro Inoue until 2016 and joined the Theg lab that year when Kentaro was tragically killed in a traffic accident. He worked as a postdoc in Hans-Henning Kunz's lab at Washington State University in Pullman, WA and then moved to his current position at Elemental Enzymes St. Louis. Thesis title: Evolution and Sorting of Chloroplast Outer Membrane Beta-Barrel Proteins

• Iniyan Ganesan - Plant Biology Graduate Student from 2014 - 2020. He is currently a postdoc in Nils Wiedermann's group in Freiburg, Germany. Thesis title: Mechanisms of Protein Translocation in Chloroplasts and Bacteria

• Anthony Asher - BMCDB Graduate Student from 2014 - 2020. Thesis title: Ion Conductivity and Interfacial Protons at the Pisum sativum Thylakoid Lumen

• Lucas Mckinnon - Plant Biology Graduate Student from 2014 - 2020. Lucas was a graduate student with Kentaro Inoue until his 2016, and joined the Theg lab after Kentaro's death. He is now working for Pioneer in St. Louis. Thesis title: Interplay Between Disulfide Bond Formation, Membrane Lipids, and pH in the Folding of Plastidic Type I Signal Peptidase 1 and Implications For Other Thylakoid Proteins

• Laura Klasek - Plant Biology Graduate Student from 2014 - 2020. Laura was also a graduate student with Kentaro Inoue until he was killed, and joined the Theg lab in 2016. Kentaro was tragically killed in a traffic accident. She currently works for Elemental Enzymes in St. Louis. Thesis title:Chaperonin-Mediated Targeting of Plastidic Type I Signal Peptidase 1

• Hope Hao - Plant Biology Graduate Student from 2016-2022, Postdoc for 6 months until 2023. Currently a postdoc in Randy Schekman's lab at UC-Berkeley. Thesis title:Analysis of the Mechanism of Protein Transport via the Twin-arginine Translocation Pathway

• Christine Zhou - Undergraduate Researcher, and 2022 CBS Undergraduate of the Year. Currently a graduate student in the Cancer Biology Program at Stanford

• Jorge Escobar - Postdoctoral Researcher, 2022-2023

Click here to see photos of some (alas, not all) of the undergraduates and high school students who once worked in the lab

Click here or here to see a description of a postdoctoral position currently open in the lab (both links describe the same position)

  The drawing of the chloroplast on this page came from Matej Lexa's The Virtual Cell.