Related Experiment Video
Updated: Aug 8, 2026

Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution
Published on: June 1, 2017
Energetics of proline transport in corn mitochondria
T E Elthon1, C R Stewart, W D Bonner
1Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Abstract:
The mechanism of proline entry into the matrix region of isolated corn mitochondria (Zea mays L. Mo17 x B73) was investigated by measuring osmotically induced changes of mitochondrial size (changes in A(520)) in combination with oxygen uptake measurements. Using NADH oxidation to generate the electrochemical gradient, we have determined that proline transport is stereospecific and that it can be inhibited by the proline analog l-thiazolidine-4-carboxylic acid.The energetics of proline transport was investigated by measuring the effects of FCCP (p-trifluoromethoxycarbonyl cyanide phenylhydrazone) and valinomycin on mitochondrial swelling and substrate oxidation. Proline transport and resulting oxidation were found to be partially dependent upon the energy of the electrochemical gradient. At low proline concentrations, entry was found to be primarily independent of the gradient (based on insensitivity to FCCP), whereas at higher proline concentrations a gradient-dependent mechanism became involved. Results with valinomycin indicated that proline transport and oxidation are dependent upon the pH potential across the membrane rather than the electrical (membrane) potential.
Related Concept Videos
Energy to Drive Translocation
Generally, polypeptides are unfolded by two distinct...
Protein Transport into the Inner Mitochondrial Membrane
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Mitochondrial Protein Sorting
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Chemiosmosis
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Chemiosmosis and ATP Synthesis
The ADP/ATP Carrier Protein

