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Fig. 1 | Stem Cell Research & Therapy

Fig. 1

From: Stem cells and COVID-19: are the human amniotic cells a new hope for therapies against the SARS-CoV-2 virus?

Fig. 1

SARS-CoV-2 structure and cell entry. a The coronavirus (CoVs) structure is complex and includes the three principal structural proteins: the spike glycoprotein (S), the transmembrane glycoprotein (M), and the nucleocapsid protein (N). The glycoprotein S is found in the viral envelope. The envelope (E) protein is a minor transmembrane protein present in the structural region. The CoVs genome is formed by a positive sense single-stranded RNA of 30 kb in size. b As a coronavirus, SARS-CoV-2 uses the S glycoprotein to facilitate entry to the host cell. This virus principally targets the respiratory epithelial cells, that express the angiotensin-converting enzyme 2 receptor (ACE2). The S protein binds to ACE2 allowing the virus access to the host cells cytosol. Proteases like TMPRRS2, cathepsin, or furin, help to viral and cellular membranes fusion through the S protein cleavage. After the viral entry, the replicase gene from the virion genomic RNA is translated. Then, the viral RNA is synthesized and the replicase complexes assembly. In the endoplasmic reticulum occurs the translation of the structural glycoproteins S, M, and E. All the translated proteins interact for CoVs assembling. Once the virions are formed, they are transported to the host cell surface in vesicles and then released by exocytosis. (This figure was created with BioRender.com)

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