@article{ehsan_ray_phinney_wang_huber_clouse_2005, title={Interaction of Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase with a homolog of mammalian TGF-beta receptor interacting protein}, volume={43}, ISSN={["1365-313X"]}, DOI={10.1111/j.1365-313X.2005.02448.x}, abstractNote={SummaryBrassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID‐INSENSITIVE 1 (BRI1) receptor serine/threonine kinase for hormone perception and signal transduction. In mammals, the transforming growth factor‐beta (TGF‐β) family of polypeptides modulate numerous aspects of development and are perceived at the cell surface by a complex of type I and type II TGF‐β receptor serine/threonine kinases. TGF‐β receptor interacting protein (TRIP‐1) is a cytoplasmic substrate of the TGF‐β type II receptor kinase and plays a role in TGF‐β signaling. TRIP‐1 is a WD domain protein that also functions as an essential subunit of the eIF3 eukaryotic translation initiation factor in animals, yeast and plants. We previously cloned putative TRIP‐1 homologs from bean and Arabidopsis and found that transgenic Arabidopsis plants expressing antisense TRIP‐1 RNA exhibited a broad range of developmental defects including some morphological characteristics that resemble the phenotype of BR‐deficient and ‐insensitive mutants. We now show that the BRI1 kinase domain phosphorylates Arabidopsis TRIP‐1 on three specific sites in vitro (Thr‐14, Thr‐89 and either Thr‐197 or Ser‐198). Co‐immunoprecipitation experiments using antibodies against TRIP‐1, BRI1 and various fusion proteins strongly suggest that TRIP‐1 and BRI1 also interact directly in vivo. These findings support a role for TRIP‐1 in the molecular mechanisms of BR‐regulated plant growth and development, possibly as a cytoplasmic substrate of the BRI1 receptor kinase.}, number={2}, journal={PLANT JOURNAL}, author={Ehsan, H and Ray, WK and Phinney, B and Wang, XF and Huber, SC and Clouse, SD}, year={2005}, month={Jul}, pages={251–261} }