Question

A 38-year-old previously healthy man is rushed to the emergency department due to the acute onset of severe, diffuse abdominal pain, intractable vomiting, and voluminous watery diarrhea. He also complains of a painful, burning sensation in his hands and feet. His spouse notes that he started a new job two weeks ago at an industrial plant that manufactures pressure-treated lumber and specialized agricultural compounds. On physical examination, his blood pressure is 90/55 mmHg, and his pulse is 115/min. He appears profoundly dehydrated, and a distinct garlic-like odor is noted on his breath. An electrocardiogram is obtained and demonstrates a prolonged QTc interval. Which of the following cellular targets is most likely directly inhibited by the primary toxin responsible for this patient's presentation?