Figure 6

Schematic representation of the role of ANT4 isoform in bioenergetics during spermatogenesis. The glucose-6-phosphatases 2 and 3 (G6PC) generates ATP from glucose 6-P (G-6P) produced by the cytoplasmic hexokinase, HK. The ATP⁴⁻ is imported into mitochondria across the MOM (mitochondrial outer membrane) through the voltage-dependent anion channel (VDAC), and then across the MIM (the mitochondrial inner membrane) by the ANT4 isoform. ATP⁴⁻ contributes to the maintenance of the mitochondrial membrane potential (ΔΨm) in spermatozoid mitochondria. The hydrolysis of imported glycolytic ATP⁴⁻ by the F1 component of the ATP synthase leads to 1 - the release of ADP³⁻ in mitochondria with the gain of a negative charge on the matrix side; and 2 - the ejection of a proton into the intermembrane space through the F0 component.