Structure of a Helical Signaling Domain from Cas
EMSL Project ID
2589
Abstract
The cellular responses to integrin signals are coordinated through specific protein-protein interactions. In this project we focus on an adaptor protein called Cas that becomes phosphorylated upon integrin/ligand binding, forms complexes with a number of signaling proteins and switches on and off downstream signals. The tyrosine-phosphorylation level of Cas correlates well with the transforming phenotype of cells and is thought to play an essential role in the process of cell transformation. Recently, it has been recognized that Cas is identical to the BCAR-1 gene that causes resistance to anti-estrogen drugs (tamoxifen) in breast cancer cells. Adaptor proteins such as Cas interact with a number of different molecules. The interacting surfaces between these pairs of proteins are potential targets for drug design, but structural details of the partner molecules must be known. Cas contains a 'serine-rich' region that is serine-phosphorylated following integrin-mediated cell adhesion. Serine-phosphorylation is important for interactions with 14-3-3 protein that plays a chaperone role to modulate signal transduction pathways. The Cas/14-3-3 complex may be involved in activation of the Erk pathway. The 3D structure of 14-3-3 protein is known and the goal of this project is to determine the structure of Cas serine-rich domain that binds to it. This domain, ~160 residues long, is highly helical and exhibits rather degenerate chemical shifts. Hence, it presents a challenge for NOESY assignment and structure determination. Also, while we have assigned most of the backbone resonances, side chain assignment proved difficult since signals from many gamma, delta and epsilon atoms are not observed in the C(CO)NH and H(CCO)NH experiments using fractionally deuterated sample. We will also record 4D 13C/13C and 13C/15N-edited NOESY experiments to obtain more unambiguous distance restraints for structure calculation. All the experiments will greatly benefit from data acquisition at high field to relieve spectral overlap and improve resolution.
Project Details
Project type
Capability Research
Start Date
2002-10-15
End Date
2004-10-22
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
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F Nasertorabi, Briknarova K, ML Havert, E Eggleston, DW Hoyt, C Li, AJ Olson, K Vuori, and KR Ely. 2005. "The Serine-rich Domain from Crk-associated Substrate (p130Cas) is a Four-helix Bundle." Journal of Biological Chemistry 280(23):21908-21914.