The hypothesis is tested that Jun–Fos activator protein-1 coiled coil inter-actions are dominated during late folding events by the formation of intri-cate intermolecular electrostatic contacts. A previously derived cJun–FosW was used as a template as it is a highly stable relative of the wild-type cJun–cFos coiled coil protein (thermal melting temperature = 63 C versus 16 C), allowing kinetic folding data to be readily extracted.