Related Experiment Video
Updated: Jul 9, 2026

A High-throughput Cre-Lox Activated Viral Membrane Fusion Assay to Identify Inhibitors of HIV-1 Viral Membrane Fusion
Published on: August 14, 2018
Restricted lateral mobility of plasma membrane CD4 impairs HIV-1 envelope glycoprotein mediated fusion
Satinder S Rawat1, Christina Zimmerman, Benitra T Johnson
1CCRNP, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702-1201, USA.
Abstract:
We investigated the effect of receptor mobility on HIV-1 envelope glycoprotein (Env)-triggered fusion using B16 mouse melanoma cells that are engineered to express CD4 and CXCR4 or CCR5. These engineered cells are resistant to fusion mediated CD4-dependent HIV-1 envelope glycoprotein. Receptor mobility was measured by fluorescence recovery after photobleaching (FRAP) using either fluorescently-labeled antibodies or transient expression of GFP-tagged receptors in the cells. No significant differences between B16 and NIH3T3 (fusion-permissive) cells were seen in lateral mobility of CCR5 or lipid probes. By contrast CD4 mobility in B16 cells was about seven-fold reduced compared to its mobility in fusion-permissive NIH3T3 cells. However, a CD4 mutant (RA5) that localizes to non-raft membrane microdomains exhibited a three-fold increased mobility in B16 cells as compared with WT-CD4. Interestingly, the B16 cells expressing the RA5 mutant (but not the wild type CD4) and coreceptors supported HIV-1 Env-mediated fusion. Our data demonstrate that the lateral mobility of CD4 is an important determinant of HIV-1 fusion/entry.
Related Concept Videos
Inhibitors of Virion Maturation and Assembly
Inhibitors Of Virion Release
Membrane Fluidity
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Retrovirus Life Cycles
Protein Diffusion in the Membrane

