Fig. 6. Schematic representation of transportation and utilization of glucose phosphate in C. parvum.

C. parvum has multiple pathways to transport and utilize hexoses for generating energy. Glucose from the gut lumen can be transported into epithelial cells through the action of host GLUT1 or GLUT2 receptors, then phosphorylated to G6P by HK1 or HK2. Glucose in the host cells could be transported into Cp by CpGT1 and G6P could be transported into Cp by CpGT1 and CpGT2 at the feeder organelle. The parasitophorous vacuole does not extend beneath the parasite but curves upward at an electron dense boundary to meet the parasite plasma membrane (see EM examples in Fig. 1). Once in the parasite cytosol, glucose can be phosphorylated by hexokinase (CpHK) and used for glycolysis or converted to G1P and used for amylopectin synthesis. GLUT1/2, human glucose transporter 1 or 2; HK1/2, human hexokinase 1 or 2. Image generated with assistance from Abigail Kimball.