Fig. 2

a Cartoon representation of the N-terminal protease-resistant domain. The residues making up Region 1 and Region 2 (see text for details) are highlighted as light brown and cyan coloured spheres respectively. b Surface representation with the same colour coding as in a and c APBS-generated electrostatic surface potential representation showing the presence of the major cleft between these two regions. All images were created using PyMOL visualisation software