Review Question - QID 215065

A 1-year-old Caucasian boy is brought to urgent care by his mother for fever and a worsening cough productive of green sputum for 3 days. He has also had bulky, foul-smelling stools that leave oily streaks on his diapers for the past month. He has had 5 prior episodes of bacterial pneumonia. The patient and his mother recently immigrated to the United States from Mexico. His mother did not receive any prenatal care. The patient’s temperature is 102.3°F (39.1°C), blood pressure is 98/62 mmHg, pulse is 140/min, and respirations are 30/min. Oxygen saturation is 90% on room air. Physical exam reveals a fussy toddler with reduced breath sounds and crackles over the left lower lung field. Which of the following best describes the normal function of the defective protein with respect to ion transport in this patient (Figure A)?