[Formula: see text]H, [Formula: see text]C and [Formula: see text]N assignments of human Grb2 free of ligands.

Growth factor receptor-bound 2 (Grb2) is an important link in the receptor tyrosine kinase signaling cascades. It is involved in crucial processes, both physiological (mainly embryogenesis) and pathological (different types of cancer). Several binding partners of all three domains (SH3-SH2-SH3) of this adaptor protein are well described, such as ErbB family members for the SH2 domain and Sos for the SH3 domains. How the different domains interact with each other, both structurally and functionally, is still unclear. These interactions could be essential for regulation processes, and therefore are of great interest. Although a lot of structural data on Grb2 exist, they describe either individual domains, ligand-bound conformations, or frozen pictures of the protein captured by crystallography. Here we report the assignment of backbone and of [Formula: see text] chemical shifts of full-length, apo-Grb2 in solution. In addition to the assigned conformation corresponding to three well-folded domains, a set of peaks compatible with the presence of an unfolded conformation of the N-terminal SH3 domain is observed. This assignment paves the way for future studies of inter-domain interactions and dynamics that have to be taken into account when studying the regulation of Grb2 interactions and signaling pathways.