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We are studying the ubiquitin/proteasome pathway using the model plant, Arabidopsis thaliana. We seek to identify components of the machinery responsible for the degradation of proteins, understand the mechanisms used to regulate ubiquitination, and characterize the cis-acting signals that mediate the recognition of the substrates by the proteolytic machinery. Our lab focuses on three major projects.
1. The RUB project 2. The RING project 3. The Auxin Signaling Project
dsRUB1 plant with an exaggerated apical hook
Sophia's beautiful diagram of the RING structure
Graph showing auxin-mediated acceleration of IAA1:LUC degradation
Dark-grown 4-day-old Arabidopsis thaliana
seedling expressing dsRUB1 under the control
of the constitutive CaMV 35S promoter
(Bostick et al, 2004)
General structure for a RING-HC domain showing spacing between metal-binding residues
(Stone et al, 2005)
Auxin accelerates the degradation of IAA1:LUC
in Arabidopsis seedlings
(Zenser et al, 2001)
We are studying the functions of RUB1, RUB2, and RUB3 in Arabidopsis. Covalent attachment of the ubiquitin-like protein RUB (NEDD8 in mammals) to the cullin subunit of SCF complexes appears to regulate their E3 ubiquitin ligase activity. We are working to understand the role of the RUB proteins in plant growth and development, with a particular emphasis on regulation of the ethylene biosynthesis pathway.
We are examining the activity of another family of proteins containing RING and variant RING domains. These domains have been implicated in the E3 ubiquitin ligase activity of many proteins. We seek to identify putative proteins containing these domains, verify their ligase activity using in vitro ubiquitination assays, identify interacting partners, and characterize their function in vivo by studying the phenotypes of plants with mutations in RING-domain-containing proteins.
Auxin signal transduction requires the ubiquitin/proteasome pathway. We are interested in studying the degradation of the AUX/IAA family of transcriptional repressors as well as other components of auxin signaling pathways. We hope to characterize the regions required for recognition of the proteolytic targets, and to learn more about the ways in which auxin affects the rate of proteolysis of specific substrates.
 
Happy, smiling Callis lab members
 
 
 
 
Top row : Jonathan Gilkerson, Sophia Stone, Edward Kraft
Middle row: Judy Callis, Mandy Hsia, Kate Dreher
Lower row: Stephanie and Kyle Lochhead, Sara Hotton, Jemma Jowett, Kim Nguyen, Alfred Tobias, Erin Fuller
Not present: Mai Dao, Minh Huynh, Sinnott Murphy, Christina Tan, Linh Tran
 
     
Graduate students from the BMB (Biochemistry and Molecular Biology), GGG (Genetics), CDB (Cell and Developmental Biology), and PBGG (Plant Biology Graduate Group) programs and undergraduate students from many disciplines work in the Callis lab.

Judy Callis
University of California, Davis
Section of Molecular and Cellular Biology
One Shields Avenue
Davis, CA 95616
office: 103A Briggs Hall (530-752-1015)
lab: 103 Briggs Hall (530-752-1014)
departmental fax (530-752-3085)
jcallis@ucdavis.edu

Home
Research Interests
Publications
Lab Members
Useful Links
People and Places
Callis Courses
Contact Us