Structural and biophysical characterisation of agrin laminin G3 domain constructs

Abstract

Agrin mediates accumulation of acetylcholine receptors (AChRs) at the developing neuromuscular junction, but has also been implicated as a regulator of central nervous system (CNS) synapses. A C-terminal region of agrin (Ag-C20) binds to the 3 subunit of the sodium-potassium ATPase (NKA) in CNS neurons suggesting that 3NKA is a neuronal agrin receptor, whereas a shorter agrin fragment (Ag-C15) was shown to act as a competitive antagonist. Here, we show that the agrin C22 construct, which represents the naturally occurring neurotrypsin cleavage product, constitutes a well-folded, stable domain, while the deletion of 48 residues that correspond to strands 1-4 of the agrin laminin G3 domain imposed by the agrin C15 construct leads to a misfolded protein. The Author 2010. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissionsoup.com2010 © The Author 2010. Published by Oxford University Press. All rights reserved.