Pre-assembled complexes and allosteric effects: parallels between eukaryotic phosphorylation cascades and membrane fusion during herpesviral entry

Unlike most enveloped viruses, Herpesviridae distribute cell entry functions across several viral envelope proteins. The prevailing model posits that, upon interaction with the target cell, the activating signal is transmitted from the receptor-binding to the fusion-mediating component in a signaling cascade that involves sequential interactions. However, herpesvirus entry proteins may form complexes throughout fusion. Here, we propose that—by analogy with certain eukaryotic signaling cascades—transmission of the activating signal involves pre-assembled complexes and allosteric effects.