title: GLUT-3 expression in human skeletal muscle.
abstract: Muscle biopsy homogenates contain GLUT-3 mRNA and protein. Before these studies, it was unclear where GLUT-3 was located in muscle tissue. In situ hybridization using a midmolecule probe demonstrated GLUT-3 within all muscle fibers. Fluorescent-tagged antibody reacting with affinity-purified antibody directed at the carboxy-terminus demonstrated GLUT-3 protein in all fibers. Slow-twitch muscle fibers, identified by NADH-tetrazolium reductase staining, possessed more GLUT-3 protein than fast-twitch fibers. Electron microscopy using affinity-purified primary antibody and gold particle-tagged second antibody showed that the majority of GLUT-3 was in association with triads and transverse tubules inside the fiber. Strong GLUT-3 signals were seen in association with the few nerves that traversed muscle sections. Electron microscopic evaluation of human peripheral nerve demonstrated GLUT-3 within the axon, with many of the particles related to mitochondria. GLUT-3 protein was found in myelin but not in Schwann cells. GLUT-1 protein was not present in nerve cells, axons, myelin, or Schwann cells but was seen at the surface of the peripheral nerve in the perineurium. These studies demonstrated that GLUT-3 mRNA and protein are expressed throughout normal human skeletal muscle, but the protein is predominantly found in the triads of slow-twitch muscle fibers.
authors.affiliation: Department of Internal Medicine, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555, USA. cstuart@utmb.edu
authors.forename: C A
authors.initials: CA
authors.lastname: Stuart
authors.forename: G
authors.initials: G
authors.lastname: Wen
authors.forename: B H
authors.initials: BH
authors.lastname: Peng
authors.forename: V L
authors.initials: VL
authors.lastname: Popov
authors.forename: S D
authors.initials: SD
authors.lastname: Hudnall
authors.forename: G A
authors.initials: GA
authors.lastname: Campbell
mesh_terms: D000328:Adult; D005455:Fluorescent Antibody Technique; D051274:Glucose Transporter Type 3; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000648:ultrastructure; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism* / Q000648:ultrastructure; D009246:NADH Tetrazolium Reductase / Q000378:metabolism; D009419:Nerve Tissue Proteins; D010525:Peripheral Nerves / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013127:Spinal Nerves / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D051274:Glucose Transporter Type 3; D009004:Monosaccharide Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C495687:SLC2A3 protein, human; D009246:NADH Tetrazolium Reductase