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

FEBS Letters

Klip, Amira²  Ackerley, Cameron¹  Ramlal, Toolsie²  He, Lijing²  Marette, André²  Lavoie, Louis² 

[1] Department of Pathology, The Hospital for Sick Children, Toronto, Ont. M5G 1X8, Canada;Division of Cell Biology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada

关键词: Immunogold labeling;    Muscle membrane;   

DOI  :  10.1016/0014-5793(95)00507-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown