Letter to the Editor: Sequence-specific resonance assignments and partial unfolding of extracellular domains II and III of E-cadherin

Epithelial cadherin (E-cadherin) is a transmembrane receptor that plays a vital role in Ca2C-dependent ho-motypic cell–cell adhesion processes (Takeichi, 1991). The extracellular domain of E-cadherin contains five tandem repeats of about 100 amino acid residues, and is responsible for recognizing cadherin molecules of the same type in a calcium-dependent manner (for a review, see Alattia et al., 1999). The determination of the three-dimensional structure and dynamics of the cadherin extracellular domain in the presence and in the absence of Ca2C should help us understand how cadherin interacts with Ca2C ions and mediates cell adhesion functions. Methods and results A recombinant protein containing extracellular do-mains II and III of mouse E-cadherin (residues 109– 333; MW 24 kDa) was cloned and expressed using a modified version of the pET 15b expression sys-tem (Novagen) and purified to homogeneity using the manufacturer’s standard procedure. Unlabeled, 15N-labeled, or 13C/15N-labeled protein solution was pre