Table 1.

Static approach to investigate the role of mitochondrial transport in energy metabolism. Pro vs. Contra.

Biological Sample	Approach	Pro vs. Contra
Tissue/cell	Carrier protein/enzyme purification	Pro: can give evidence for the existence and study of metabolite binding to the carrier/enzyme Contra: NATM
Proteins, lipids	Reconstitution study	Pro: can show the capability of the isolated protein to work as a carrier when present in proteoliposomes/of the isolated enzyme to catalyze the reaction Contra: NATM
Proteins	Sequencing	Pro: can give the possibility to investigate carrier protein/enzyme structure and metabolite binding sites Contra: NATM
Cell/cell component	Cell fractionation	Pro: can show both carrier protein/enzyme localization and identification of the organelles involved in transport/catalysis Contra: NATM
No biological system	Bioinformatic analysis	Pro: can give a first predictive insight into the localization and the role of a protein and in comparative genetics Contra: NATM
Cell/cell component	Immunological analysis	Pro: can give evidence for the existence and the amount of a protein independently on its catalytic properties and localization Contra: NATM
Cell/cell component	Confocal microscopy	Pro: can show localization of a protein in vitro Contra: NATM
Cell/cell component	Magnetic resonance spectroscopy	Pro: allows to identify the levels of some metabolites in specific anatomical structures, Contra: NATM
Cell/cell component	High-resolution mass spectroscopy	Pro: can show that enriched substrate can enter mitochondria by using 13C and 2-2H labels Contra: NATM
Cell/cell component	Transmission electron microscopy	Pro: can show the mitochondrial localization Contra: NATM
Cell/cell component	High-performance liquid chromatography (HPLC)	Pro: can give qualitative/quantitative analysis in biological sample Contra: NATM

Abbreviation: NATM, nothing about transport and metabolism both in vitro and in vivo.