Review Question - QID 212865

A 22-year-old woman presents to the emergency department with a 2-day history of severe blistering. She says that she woke up 2 days ago with a number of painful blisters in her mouth and has since been continuing to develop blisters of her cutaneous skin all over her body and the mucosa of her mouth. She has no past medical history and has never experienced these symptoms before. Physical exam reveals a diffuse vesicular rash with painful, flaccid blisters that separate easily with gentle rubbing. The function of which of the following proteins is most likely disrupted in this patient?