Biochemical and functional evidences for a GLUT-4 homologous protein in avian skeletal muscle.
The characteristics and modulation of glucose transport were investigated in skeletal muscles of 5-wk-old Muscovy ducklings (Cairina moschata). Glucose uptake by sarcolemmal vesicles isolated from gastrocnemius muscle followed typical Michaelis-Menten kinetics with a K(m) value (17 mM) similar to that described in equivalent mammalian preparations. Western blot analysis of duckling sarcolemma using antibodies directed against rat GLUT-4 transporter revealed an immunoreactive protein of similar molecular mass (45 kDa) to that present in rats. When ducklings were killed in the postabsorptive state, GLUT-4 homologous protein was located predominantly (80%) in intracellular membranes. Insulin stimulation of a perfused leg muscle preparation in vitro led to the translocation of GLUT-4 homologous proteins from intracellular pools to the sarcolemma, with a subsequent increase in glucose uptake by sarcolemmal vesicles and perfused muscles. Glucose transport was positively controlled by the metabolic needs of skeletal muscle as reflected by the increased glucose uptake of sarcolemmal vesicles isolated from cold-acclimated ducklings. Present results, therefore, demonstrate, for the first time in an avian species, the existence in skeletal muscle of a glucose transporter showing molecular and functional homologies with the mammalian GLUT-4 transporter.
Thomas-Delloye
V
V
Laboratoire de Physiologie des Régulations Energétiques, Cellulaires et Moléculaires, Unité Mixte de Recherche Centre National de la Recherche Scientifique-Université Claude Bernard Lyon 1, Faculté des Sciences, F-69622 Villeurbanne, France.
Marmonier
F
F
Duchamp
C
C
Pichon-Georges
B
B
Lachuer
J
J
Barré
H
H
Crouzoulon
G
G
D000064:Acclimatization; D000818:Animals; D004372:Ducks; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D061389:Insulin, Regular, Pork; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism
D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D061389:Insulin, Regular, Pork; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495677:SLC2A1 protein, human; C495692:SLC2A4 protein, human; C495694:Slc2a4 protein, rat; C000006:insulin, neutral; D005947:Glucose