At 04:14 PM 1/10/2006, you wrote:
Hello All.
I'm trying to find some information on the specific types of cells
that use a shuttle mechanism to move NADH into the mitochondria. Also,
if anyone has any suggestions about where to get some more specifics
on this process of why we get 36-38 ATP I would appreciate it.
Thanks! Hope everyone has a great semester!
Darren Mattone
I thought I might find something on the NADH transport in Alberts et al.,
Molecular Biology of the Cell, but I came up empty-handed. While I do not
remember my source, back when I was looking into this to write the first
edition of my textbook, I found information that mitochondria cannot import
NADH from the cytosol. The NADH generated by glycolysis does not (to my
knowledge) enter them. Below is an excerpt from what I wrote for the
A&P-level student reader (and what has so far survived a decade of peer
review without adverse comment). This may be more superficial than what
you're looking for, but perhaps will be of a little help. Thank you for
asking, Darren. If anyone else has information to contradict this, then I
need to make another textbook correction!
Furthermore, the NADH generated by glycolysis cannot enter the
mitochondria and donate its electrons directly to the electron-transport
chain. In liver, kidney, and myocardial cells, NADH passes its electrons to
malate, a "shuttle" molecule that delivers the electrons to the beginning of
the electron-transport chain. In this case, each NADH yields enough energy
to generate 3 ATP. In skeletal muscle and brain cells, however, the
glycolytic NADH transfers its electrons to glycerol phosphate, a different
shuttle that donates the electrons farther down the electron-transport chain
and results in the production of only 2 ATP. Therefore the amount of ATP
produced per NADH differs from one cell type to another and is still unknown
for others.
Ken Saladin