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Insulin‐responsive glucose transporters are concentrated in a cell surfacederived membrane fraction of 3T3‐L1 adipocytes
Author(s) -
Lange Klaus,
Brandt Ursula
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80615-p
Subject(s) - glucose transporter , cytochalasin b , vesicle , population , membrane , transporter , chemistry , homogenization (climate) , insulin , biophysics , biochemistry , cell , biology , endocrinology , biodiversity , ecology , demography , sociology , gene
The recently proposed mechanistic concept of a receptor‐regulated entrance compartment for hexose transport formed by microvilli on 3T3‐L1 adipocytes predicted a preferential localization of glucose transporters in these structures. The cytochalasin B‐binding technique was used to determine in basal and insulin‐stimulated cells the distribution of glucose transporters between plasma membranes, low density microsomes (LDM) and two cell surface‐derived membrane fractions prepared by a hydrodynamic shearing technique. The shearing procedure applied prior to homogenization yielded a low density surface‐derived vesicle (LDSV) fraction which contained nearly 60% of the cellular glucose transporters and the total insulin‐sensitive transporter pool. The rest of the glucose transporter population was localized within the plasma membrane (5%) and the LDM fraction (37%). Pretreatment of the cells with insulin (20for 10 min) reduced the transporter content of the LDSV fraction by 40% and increased that of the plasma membrane fraction 4‐fold. The transporter containing LDSV fraction was clearly differentiated from the LDM fraction by its low specific galactosyltransferase activity and its insulin‐sensitivity. Scanning electron microscopy revealed that the LDSV fraction contained a rather uniform population of spherical vesicles of 100–200 nm in diameter.