Key Takeaways
- •Matrix protein 1 (M1) is the most abundant protein in the influenza virion.
- •M1 consists of 252 amino acids organized into three domains.
- •Inside the virion, M1 forms a continuous protein layer on the inner surface of the viral lipid envelope.
What Is Matrix Protein 1?
Matrix protein 1 (M1) is the most abundant protein in the influenza virion. It plays essential roles during the entire viral replication cycle, including virus entry, uncoating, assembly, and budding.
M1 consists of 252 amino acids organized into three domains. Each domain contains tightly packed alpha-helical bundles connected by short linker regions. This structure enables M1 to form multimers and interact with other viral components.
How Does Matrix Protein 1 Interact with Viral Components?
Lipid Envelope
Inside the virion, M1 forms a continuous protein layer on the inner surface of the viral lipid envelope. This layer provides mechanical stability and influences the shape of the virus particle. Influenza virions can be either spherical or filamentous.
Clinical isolates often show a high proportion of filamentous virions. These filaments may help spread the virus to neighboring cells. In contrast, spherical particles are more common after repeated passage in eggs or cell culture and are thought to be more efficient for aerosol transmission between hosts.
The amino acid sequence 1-164 of M1 is responsible for binding to the lipid envelope.
Viral Ribonucleoproteins (vRNPs)
The continuous M1 layer on the inner side of the viral lipid bilayer anchors the viral ribonucleoproteins (vRNPs). The vRNPs comprise the viral RNA, the associated nucleoprotein (NP), and a polymerase complex, which together form a functional unit. Binding of M1 appears to suppress transcription of the viral genome until M1 is removed.
The amino acid sequence 165-252 of M1 is responsible for binding to vRNPs.
Matrix Protein 2 (M2) Ion Channel
M1 is linked to the function of the Matrix protein 2 (M2) proton channel. M2 acidifies the virion interior after it is internalized by endocytosis of the host cell. This triggers M1 to dissociate from vRNPs.
Surface Glycoproteins Hemagglutinin (HA) and Neuraminidase (NA)
M1 interacts with the cytoplasmic tails of Hemagglutinin and Neuraminidase. This interaction helps recruit M1 into lipid rafts, which are specialized membrane domains.
Nuclear Export Protein (NEP)
Nuclear Export Protein binds to the M1-vRNP complex. In polarized epithelial cells, this promotes nuclear export of the complex toward the apical plasma membrane, where virus assembly occurs.
Function of Matrix Protein 1 in the Viral Life Cycle
Viral Entry and Uncoating
After viral entry by endocytosis, the low pH inside the endosome activates the M2 ion channel. Protons enter the virion and lower the pH inside. This causes M1 to dissociate from vRNPs. The released vRNPs are then transported to the nucleus for transcription and replication.
Regulation of Transcription
The dissociation of M1 is necessary to initiate viral RNA synthesis. NEP-mediated export of M1-vRNP complexes ensures proper timing of replication and assembly.
Virus Assembly and Budding
M1 plays a central role in assembling new virus particles. During budding, M1 forms a multimeric network beneath the viral envelope. This structure is stabilized by interactions with Hemagglutinin (HA), Neuraminidase (NA), and the lipid bilayer. M1 ensures the proper incorporation of vRNPs and surface proteins into new virions.
Conclusion
Matrix protein 1 is essential for influenza virus replication. It provides structural support, regulates genome release, controls transcription, and enables efficient assembly. Due to its central role and high abundance, M1 is a promising target for antiviral strategies and drug development. For researchers studying influenza proteins, our Peptide Glossary offers definitions of key terms, and our BPC-157 Research Guide provides an example of how peptide tools can support research. You can also explore our Free Peptide Tools for calculating dosages and stability.
Literature
Dadonaite, Bernadeta et al. "Filamentous influenza viruses." The Journal of general virology vol. 97,8 (2016): 1755-1764. doi:10.1099/jgv.0.000535
Eisfeld, Amie J et al. "At the centre: influenza A virus ribonucleoproteins." Nature reviews. Microbiology vol. 13,1 (2015): 28-41. doi:10.1038/nrmicro3367
Related Research Compounds
Looking for high-purity research peptides? Browse our catalog for HPLC-verified compounds.
| Compound | Purity | Size | Price |
|---|---|---|---|
| BPC-157 5mg | >99% | 5mg | $34.00 |
| BPC-157 10mg | >99% | 10mg | $44.00 |