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Title: AN ARABIDOPSIS PROTEIN WITH SEQUENCE SIMILARITY TO ANIMAL TGF-BETA RECEPTOR INTERACTING PROTEIN IS PHOSPHORYLATED BY THE BR11 RECEPTOR KINASE IN VITRO

Author
item EHSAN, HASHIMUL - NC STATE UNIV
item RAY, WILLIAM - MICHIGAN STATE UNIV
item Huber, Steven
item CLOUSE, STEVEN - NC STATE UNIV

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/25/2003
Publication Date: 5/25/2003
Citation: Ehsan, H., Ray, W.K., Huber, S.C., Clouse, S.D. 2003. An arabidopsis protein with sequence similarity to animal tgf-beta receptor interacting protein is phosphorylated by the br11 receptor kinase in vitro [abstract]. American Society of Plant Biologists. Available: http://abstracts.aspb.org/pb2003/public/M12/5068.html

Interpretive Summary:

Technical Abstract: Brassinosteroids (BRs) regulate the expression of numerous genes associated with plant development and require the activity of BRI1, a Ser/Thr receptor kinase, to realize their effects. The Transforming Growth Factor-beta (TGF-beta) family of peptides, acts via Ser/Thr receptor kinases to prominently impact several pathways involved in animal development and adult homeostasis. In animals, TGF-beta Receptor Interacting Protein (TRIP-1) is an intracellular substrate of the TGF-beta Type II receptor kinase and plays an important role in TGF-beta signaling. We recently found that transcript levels of TRIP-1 homologs in plants are regulated by BR treatment under a variety of conditions, and that transgenic plants expressing antisense TRIP-1 RNA exhibit a broad range of developmental defects including some that resemble the phenotype of BR-deficient and -insensitive mutants. Furthermore, we have shown that recombinant BRI1 kinase domain phosphorylates recombinant TRIP-1 in vitro. These findings suggest that TRIP-1 may mediate some of the molecular mechanisms underlying the regulation of plant growth and development by BRs, possibly as a direct substrate of the BRI1 receptor kinase. We have identified three Thr residues in TRIP-1 that are the putative targets of BRI1 phosphorylation, using MALDI and Q-TOF mass spectrometry. Immunoprecipitation followed by mass spectrometry is also being used to identify in vivo phosphorylation sites of TRIP-1 and their possible dependence on an active BRI1