Related Experiment Video

Updated: Aug 23, 2026

Co-immunoprecipitation of the Mouse Mx1 Protein with the Influenza A Virus Nucleoprotein
09:39

Co-immunoprecipitation of the Mouse Mx1 Protein with the Influenza A Virus Nucleoprotein

Published on: April 21, 2015

The influenza virus ion channel and maturation cofactor M2 is a cholesterol-binding protein

Cornelia Schroeder1, Harald Heider, Elisabeth Möncke-Buchner

  • 1Abteilung Virologie, Institut für Mikrobiologie und Hygiene, Universität des Saarlandes, Homburg/Saar, 66421 Homburg, Germany.

European Biophysics Journal : EBJ
|June 29, 2004
PubMed

Insights

Cholesterol is not essential for the influenza M2 protein's ion channel function or its cytotoxicity. This finding impacts understanding of M2's role in virus budding and drug resistance.

Area of Science:

  • Virology
  • Molecular Biology
  • Membrane Biophysics

Background:

  • Influenza M2 protein's proton channel activity is crucial for virus uncoating and HA maturation.
  • M2 also influences viral shape through interactions with M1 protein in membrane rafts.
  • M2 exhibits cytotoxicity and its channel can be blocked by rimantadine.

Purpose of the Study:

  • To investigate the role of cholesterol in influenza M2 protein function, including its ion channel activity, cytotoxicity, and interaction with membrane rafts.
  • To determine if cholesterol is essential for M2's rimantadine sensitivity and its proposed role in virus budding.

Main Methods:

  • Analysis of M2 protein preparations from infected cells and baculovirus expression systems for cholesterol content.
  • Sequence analysis of M2 endodomain for potential cholesterol and lipid-binding motifs.
  • Functional reconstitution of purified M2 in cholesterol-free liposomes and cytotoxicity assays in cholesterol-free E. coli.
  • Assessment of M2 association with detergent-resistant membranes.

Main Results:

  • M2 preparations contained significant amounts of cholesterol, but cholesterol was found to be nonessential for M2's proton channel activity and cytotoxicity.
  • Rimantadine-sensitive proton translocation and cytotoxicity were observed in cholesterol-free systems, demonstrating cholesterol's dispensability for these functions and drug sensitivity.
  • M2 protein associates peripherally with membrane rafts, suggesting a role at the raft/non-raft interface in viral processes.

Conclusions:

  • Cholesterol is not required for the fundamental functions of the influenza M2 protein, including its ion channel activity, cytotoxicity, and sensitivity to rimantadine.
  • M2 protein likely functions as a peripheral raft protein, potentially influencing viral budding through raft-mediated mechanisms.
  • The findings provide insights into M2's interaction with host cell membranes and its potential role in viral particle formation.

More Related Videos

Affinity Purification of Influenza Virus Ribonucleoprotein Complexes from the Chromatin of Infected Cells11:20

Affinity Purification of Influenza Virus Ribonucleoprotein Complexes from the Chromatin of Infected Cells

Published on: June 3, 2012

Imaging Cell Interaction in Tracheal Mucosa During Influenza Virus Infection Using Two-photon Intravital Microscopy08:01

Imaging Cell Interaction in Tracheal Mucosa During Influenza Virus Infection Using Two-photon Intravital Microscopy

Published on: August 17, 2018

Related Concept Videos

Leaky Scanning02:28

Leaky Scanning

During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA.  Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
Influenza01:27

Influenza

Influenza is an acute, highly communicable viral disease that affects the respiratory tract and is responsible for seasonal epidemics worldwide. Influenza A is the most prevalent type associated with widespread outbreaks and is subtyped based on two surface glycoproteins: hemagglutinin (H) and neuraminidase (N), as in H1N1. These glycoproteins are essential for viral infectivity, transmission, and immune recognition. Transmission occurs primarily through respiratory droplets and contaminated...
Inhibitors of Virion Maturation and Assembly01:19

Inhibitors of Virion Maturation and Assembly

As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...
Inhibitors Of Virion Release01:25

Inhibitors Of Virion Release

Viral replication and dissemination rely on efficient mechanisms for host cell entry, genome replication, assembly, and release. Influenza viruses, such as types A and B, are negative-sense single-stranded RNA viruses with a segmented genome, that depend on two critical surface glycoproteins to carry out these processes: hemagglutinin (HA) and neuraminidase (NA). HA initiates infection by binding to sialic acid residues on the surface of host epithelial cells, facilitating receptor-mediated...
Intralumenal Vesicles and Multivesicular Bodies01:38

Intralumenal Vesicles and Multivesicular Bodies

Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...