Related Experiment Video
Updated: Jul 20, 2026

Demonstration of Heterologous Complexes formed by Golgi-Resident Type III Membrane Proteins using Split Luciferase Complementation Assay
Published on: September 10, 2020
Heterologously expressed GLT-1 associates in approximately 200-nm protein-lipid islands
Stefan Raunser1, Winfried Haase, Cornelia Franke
1Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany.
Abstract:
The glutamate transporter GLT-1 from Rattus norvegicus was expressed at high level in baby hamster kidney (BHK-21) cells by the Semliki Forest Virus expression system. We examined the expressed GLT-1 in the plasma membrane and found that the transporter accumulates in detergent-insoluble lipid-protein assemblies. Freeze-fracture, immunogold labeling, and electron microscopy revealed that GLT-1 forms approximately 200-nm protein-rich islands in the plasma membrane. Cholesterol depletion in living cells resulted in a dispersion of the GLT-1 islands, indicating that they are the result of lipid-protein rather than protein-protein interactions. Disruption of GLT-1 islands and dispersion of GLT-1 goes along with a reduction of the glutamate transport activity. Our direct visualization of lipid-protein islands in the plasma membrane of tissue culture cells suggests that the reported clustering of glutamate transporters and their cholesterol-dependent transport activity in cells is likewise connected to their association with cholesterol-rich microdomains in the plasma membrane.
Related Concept Videos
GPI Anchoring of Proteins in the ER Membrane
GPI-anchor structure
A sequence of 11 enzymatic reactions results in the synthesis of the complete GPI anchor consisting of a hydrophobic and a hydrophilic portion. The hydrophobic portion comprises phosphatidylinositol, while the hydrophilic part comprises polar groups like phosphoethanolamine,...
Lipids as Anchors
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains the...
Protein Translocation Machinery on the ER Membrane
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Formation of Lipopolysaccharides
Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...

