Cell Signaling with Extracellular Thioredoxin and Thioredoxin-Like Proteins: Insight into Their Mechanisms of Action

Figure 5

The nucleoredoxin-like 1 gene encodes for a superthioredoxin system. (a) In the absence of RdCVF signaling mediated by the complex BSG1/GLUT1, the reduction of oxidized RdCVFL in cones by thioredoxin reductase (TXNRD) and NADPH is limited by glucose uptake rate. (b) The extracellular truncated thioredoxin RdCVF accelerates glucose uptake by its interaction with the BSG1/GLUT1 complex at the surface of cones. The concentration of NADPH produced by the pentose phosphate pathway is increased. Consequently, the reduction of RdCVFL is ameliorated so that the combination of extracellular RdCVF and intracellular RdCVFL constitutes a superthioredoxin system. Glc: glucose, lact: lactate, and ROS: reactive oxygen species. Circles represent metabolites and their diameters and their concentrations. Yellow: glycolysis, Orange: triglyceride synthesis, and purple: pentose phosphate pathway.

(a)

(b)