COVID-19 — The terror in our society
The SARS-CoV-2 virus or the COVID-19 virus is essentially an enveloped virus (refer to my previous blog). It is almost entirely composed of 4 functional proteins — The S protein, The M protein, The E protein and the N protein.
S — Spike protein
E — Envelope protein
M — Membrane protein
N — Nucleocapsid protein
The S, E and M proteins are surface proteins, which mean that they can be found on the outer surface of the virus particle. On the other hand, the N protein is an inner protein that is found inside the viral capsid.
S — proteins:
The S proteins have two parts — the top crown part called as S1 and the bottom tail structure called S2. Its main function is to allow the virus to attach to the host’s cells. Every virus has its own unique S protein which attaches itself to its own compatible receptor which lies on the surface of the cell membrane in the organism’s body. In the case of the SARS-Cov-2 virus, the S protein of the virus attaches itself to a receptor known as ACE-2 (Angiotensin Converting Enzyme — 2), which is found on the outer surface of the epithelial cells (cells underlying the surface of organs) lining the lungs, heart, kidneys and intestines. The S proteins of Covid — 19 show high affinity for the ACE-2 receptors, which may be an integral cause for its fast spread.
(taken from prosci-inc.com)
(taken from ‘Coronavirus COVID-19 | Viral Structure & Pathogenesis’ by Anatomy Zone)
As mentioned before, the S protein has two parts — the S1 and the S2. The S1 part of the protein acts as a hook to attach the virus particle to its compatible receptor i.e. ACE-2. After attaching itself to the receptor, the S2 part mediates the fusion process between the host’s and virus’ cellular membranes. This way, the virus and the cell become one, allowing it to use the cell’s help to replicate its genome.
M — proteins:
Out of the four functional proteins, these are the most abundant on the viral surface. Found on the surface of the envelope of the virus, the M proteins play a vital role in defining the shape of the viral envelope. It can be thought of as the main organizer of the assembly of the virus. It interacts with the other structural proteins of the host’s cells.
(taken from invivogen.com)
E — proteins:
The E proteins help in the replication of the virus particles. They are important for the creation of new virus particles and releasing them from the host’s cells to let it infect other cells. It is present on the surface of the viral envelope, but comes into action when it enters into the area of cellular trafficking or transport.
(taken from epigentek.com)
The M and E proteins turn the cell into workshops where the virus and our cells work together to create new viral particles.
N — proteins:
The N protein, or the nucleocapsid protein is present entwined around the virus’ genome or the RNA. It is multifunctional. It inhibits the cell’s defense mechanism, allowing the virus particle to inject it and the RNA into the cell. In the cell, it assists the RNA in replicating itself.
(taken from ‘Coronavirus COVID-19 | Viral Structure & Pathogenesis’ by Anatomy Zone)
