Review Question - QID 109725

A 37-year-old man is brought to the emergency department because he was found down on a city sidewalk. Upon presentation he is found to be disheveled with multiple poorly healed wounds on his hands and feet. He has had dozens of previous presentations for alcohol intoxication and is currently known to be homeless. Physical examination reveals multiple minor wounds, alopecia, and decreased axillary hair. Upon being aroused, the patient reveals that he has had difficulty with taste and smell and has also had severe diarrhea over the last week. The deficient substance most likely responsible for this patient's symptoms is associated with which of the following proteins?