title: Monocarboxylate transporters in subsarcolemmal and intermyofibrillar mitochondria.
abstract: Whether subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria contain monocarboxylate transporters (MCTs) is controversial. We have examined the presence of MCT1, 2, and 4 in highly purified SS and IMF mitochondria. These mitochondria were not contaminated with plasma membrane, sarcoplasmic reticulum or endosomal compartments, as the marker proteins for these sub-cellular compartments (Na+-K+-ATPase, Ca2+-ATPase, and the transferrin receptor) were not present in SS or IMF mitochondria. MCT1, MCT2, and MCT4 were all present at the plasma membrane. However, MCT1 and MCT4 were associated with SS mitochondria. In contrast, the IMF mitochondria were completely devoid of MCT1 and MCT4. However, MCT2 was associated with both SS and IMF mitochondria. These observations suggest that SS and IMF mitochondria have different capacities for metabolizing monocarboxylates. Thus, the controversy as to whether mitochondria can take up and oxidize lactate will need to take account of the different distribution of MCTs between SS and IMF mitochondria.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ont., Canada N2L 3G1.
authors.forename: Carley R
authors.initials: CR
authors.lastname: Benton
authors.forename: Shannon E
authors.initials: SE
authors.lastname: Campbell
authors.forename: Mio
authors.initials: M
authors.lastname: Tonouchi
authors.forename: Hideo
authors.initials: H
authors.lastname: Hatta
authors.forename: Arend
authors.initials: A
authors.lastname: Bonen
mesh_terms: D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D007700:Kinetics; D007773:Lactates / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry; D026901:Membrane Transport Proteins / Q000737:chemistry; D008931:Mitochondria, Muscle / Q000378:metabolism*; D027501:Monocarboxylic Acid Transporters / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009210:Myofibrils / Q000378:metabolism; D015513:Oncogene Proteins / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D020033:Protein Isoforms; D019289:Pyruvic Acid / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D011990:Receptors, Transferrin / Q000378:metabolism; D012508:Sarcolemma / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D007773:Lactates; C115081:MCTS1 protein, human; D026901:Membrane Transport Proteins; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D015513:Oncogene Proteins; D020033:Protein Isoforms; D011990:Receptors, Transferrin; C516342:Slc16a3 protein, rat; C091633:Slc16a7 protein, rat; D019344:Lactic Acid; D019289:Pyruvic Acid; D010100:Oxygen