There are three isoenzymes of 5 alpha reductase, which vary in different tissues with age.

In plants In photosynthetic organisms, NADPH is produced by ferredoxin NADP reductase in the last step of the electron chain of the light reactions of photosynthesis.

However, in a hyperglycemic state, the affinity of aldose reductase for glucose rises, meaning much higher levels of sorbitol and much lower levels of NADPH, a compound used up when this pathway is activated.

Based on the nature of the electron transfer proteins, CYPs can be classified into several groups Microsomal P450 systems in which electrons are transferred from NADPH via cytochrome P450 reductase (variously CPR, POR, or CYPOR).