Premium
The GLUT4 glucose transporter and the α 2 subunit of the Na + ,K + ‐ATPase do not localize to the same intracellular vesicles in rat skeletal muscle
Author(s) -
Lavoie Louis,
He Lijing,
Ramlal Toolsie,
Ackerley Cameron,
Marette André,
Klip Amira
Publication year - 1995
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(95)00507-6
Subject(s) - glut4 , glucose transporter , intracellular , vesicle , protein subunit , skeletal muscle , biology , atpase , biochemistry , immunogold labelling , membrane , microbiology and biotechnology , enzyme , insulin , anatomy , endocrinology , ultrastructure , gene
The GLUT4 glucose transporter and the α 2 subunit of the Na + ,K + ‐ATPase of rat skeletal muscle are two proteins which redistribute from intracellular membranes to plasma membranes following in vivo insulin stimulation. Here we show that although both proteins co‐segregate after subcellular fractionation of unstimulated rat hindlimb muscles, they do not share the same intracellular residence inside the muscle fibre. By immunogold single‐ and double‐labeling on ultrathin muscle cryosections with specific antibodies, the GLUT4 glucose transporter and the Na + ,K + ‐ATPase α 2 subunit were observed on different vesicular structures within the cell. GLUT4 was detected on subsarcolemmal and perinuclear membranes, and at the junction between myofibrillar A and I bands where triads are localized. The α 2 subunit of the Na + ,K + ‐ATPase was observed at the plasma membrane and in distinct subsarcolemmal vesicles and intermyofibrillar membranes. Quantitative analysis of double‐labeling of GLUT4 and Na + ,K + ‐ATPase α 2 subunit revealed that less than 6% of the two proteins co‐localize in the same continuous vesicular structures. The differential intracellular localization of the two proteins was further confirmed by immunopurification of GLUT4‐containing membranes from muscle homogenates, in which the α 2 subunit of the Na + ,K + ‐ATPase was found only at the same extent as the α 1 subunit of the enzyme, a protein exclusively present at the plasma membrane.