Sciencemadness Discussion Board

Mitochondrial shuttles

nitroglycol - 30-1-2009 at 20:46

As far as I understand, there are two main shuttles used to feed electrons from cytosolic NADH into the respiratory chain, the malate shuttle (which gives you a mitochondrial NADH for each cytosolic NADH) and the glycerol phosphate shuttle (which gives you QH2 via FADH2 instead, resulting in less ATP generation). Both occur in humans, but in different tissues, IIRC. The question is, why do some bother with the glycerol phosphate shuttle at all? After all, the genes for the malate shuttle are there (being as they're in the same organism and all).

Of course, the malate shuttle is more complicated, and since it involves citric acid cycle intermediates it might complicate regulation of the cycle. Is that why?

Sleep - 23-6-2009 at 03:27

The glycerol phosphate shuttle is less energetically efficient and generates more heat. It's the shuttle of choice in brown adipose (fat) tissue. The function of brown adipose tissue is to generate heat in hibernating animals, human neonati,... They contain a larger number of mitochondria than other tissue.