Picornain 3C (EC 3.4.22.28) is a protease found in picornaviruses, which cleaves peptide bonds of non-terminal sequences.
Picornain 3C’s endopeptidase activity is primarily responsible for the catalytic process of selectively cleaving Gln-Gly bonds in the polyprotein of poliovirus and with substitution of Glu for Gln, and Ser or Thr for Gly in other picornaviruses.
Picornain 3C are cysteine proteases related by amino acid sequence to trypsin-like serine proteases.
Picornain 3C is encoded by enteroviruses, rhinoviruses, aphtoviruses and cardioviruses.
These genra of picoviruses cause a wide range of infections in humans and mammals.

Picornavirus belongs to the family Picornaviridae.
Picornavirus virions are nonenveloped and the +ssRNA nonsegmented genome is encapsulated in an icosahedral protein structure made from four capsid proteins encoded by the virus.
Picornavirus viral replication typically takes place in the cytoplasm of the cell.
Picornavirus +ssRNA genome then gets translated via internal ribosome entry sites (IRES) that is recognized by host cell ribosomes for cap independent translation.
To compete with other mRNA transcripts, picornavirus destroys cap dependent translation in the host so host cell ribosomes will favor translation of viral transcripts.
+ssRNA makes –ssRNA intermediates to make more viral +ssRNA.
The genome of picornavirus is exhibited in Figure 1.
As displayed, picornavirus does not have a viral 5’ cap but instead encodes for a protein Vpg.
The absence of the 5’ cap is why the picornavirus genome depends on cap dependent translation for replication.
The genome, however, does contain a poly-A tail on the opposite end of the Vpg protein.
Both ends of the genome has UTR (untranslated regions).
The picornavirus genome has three proteins (P1, P2, P3).
P1 encodes for a proteins (VP1, VP2, VP3, and VP4) that make the capsid proteins.
P2 and P3 proteins assist in infectivity of the picornavirus to hijack and interfere with host cell functionality.
Specifically, 2B, 2C, and 3A proteins interfere with host cell function and the 3D protein encodes as the RNA polymerase.
2A and 3C act as proteinases and their function varies among the different genera of picornavirus.

Poliovirus is a member of the family Picornaviridae.
Poliovirus is transmitted through the oral-fecal route and does not always cause symptoms.
A small amount of poliovirus infections cause paralysis when the virus infects the nervous system.
Poliovirus infects host cells through inhibition of transcription machinery and function.
Polioviruses’ protease 3C is responsible for host cell transcription shut off by cleaving the TATA-binding protein and other transcription factors at glutamine-glycine sites This inhibition of transcription is caused by Protease 3C, one of Polioviruses’ 4 viral proteins encoded in its genome.
Poliovirus 3C protease replication occurs in the cytoplasm, yet is able to inhibit transcription in the nucleus without any nuclear localization.
Therefore, protease 3C depends on poliovirus 3CD protein for the translocation of 3C protease to carry out transcription inhibition in the nucleus.
The 3CD polyprotein of poliovirus consists of the precursor of both the 3C protease (3Cpro) and the 3D RNA polymerase.
3CD undergoes proteolysis, which leads to localization in the nucleus. “
The 3C protein, being of unknown function, is a product of 3CD cleavage by 2Apro”.
Poliovirus is also involved in the cleavage of eIF4E (Eukaryotic translation initiation factor 4E).
eIF4E is a protein involved in directing Eurkaryotic ribosomes in cap dependent translation.
The proteolytic cleavage of eIF4E disables the host from carrying out cap dependent translation.

Coxsackievirus belongs to the Picornaviridae family and Enterovirus genus.
Coxsackievirus is shed through stool and bodily fluids and is prevalent in children but can infection occur in adults.
Symptoms for coxsackievirus are fever, malaise, rash and blisters.
Coxsackievirus primarily infects mucosal and epithelial membranes.
3C proteinase activity in coxsackievirus causes apoptosis in
Picornain 3C (EC 3.4.22.28) is a protease found in picornaviruses, which cleaves peptide bonds of non-terminal sequences. Picornain 3C’s endopeptidase activity is primarily responsible for the catalytic process of selectively cleaving Gln-Gly bonds in the polyprotein of poliovirus and with substitution of Glu for Gln, and Ser or Thr for Gly in other picornaviruses. Picornain 3C are cysteine proteases related by amino acid sequence to trypsin-like serine proteases. Picornain 3C is encoded by enteroviruses, rhinoviruses, aphtoviruses and cardioviruses. These genra of picoviruses cause a wide range of infections in humans and mammals.
Picornavirus belongs to the family Picornaviridae. Picornavirus virions are nonenveloped and the +ssRNA nonsegmented genome is encapsulated in an icosahedral protein structure made from four capsid proteins encoded by the virus. Picornavirus viral replication typically takes place in the cytoplasm of the cell. Picornavirus +ssRNA genome then gets translated via internal ribosome entry sites (IRES) that is recognized by host cell ribosomes for cap independent translation. To compete with other mRNA transcripts, picornavirus destroys cap dependent translation in the host so host cell ribosomes will favor translation of viral transcripts. +ssRNA makes –ssRNA intermediates to make more viral +ssRNA. The genome of picornavirus is exhibited in Figure 1. As displayed, picornavirus does not have a viral 5’ cap but instead encodes for a protein Vpg. The absence of the 5’ cap is why the picornavirus genome depends on cap dependent translation for replication. The genome, however, does contain a poly-A tail on the opposite end of the Vpg protein. Both ends of the genome has UTR (untranslated regions). The picornavirus genome has three proteins (P1, P2, P3). P1 encodes for a proteins (VP1, VP2, VP3, and VP4) that make the capsid proteins. P2 and P3 proteins assist in infectivity of the picornavirus to hijack and interfere with host cell functionality. Specifically, 2B, 2C, and 3A proteins interfere with host cell function and the 3D protein encodes as the RNA polymerase. 2A and 3C act as proteinases and their function varies among the different genera of picornavirus.
Poliovirus is a member of the family Picornaviridae. Poliovirus is transmitted through the oral-fecal route and does not always cause symptoms. A small amount of poliovirus infections cause paralysis when the virus infects the nervous system. Poliovirus infects host cells through inhibition of transcription machinery and function. Polioviruses’ protease 3C is responsible for host cell transcription shut off by cleaving the TATA-binding protein and other transcription factors at glutamine-glycine sites This inhibition of transcription is caused by Protease 3C, one of Polioviruses’ 4 viral proteins encoded in its genome. Poliovirus 3C protease replication occurs in the cytoplasm, yet is able to inhibit transcription in the nucleus without any nuclear localization. Therefore, protease 3C depends on poliovirus 3CD protein for the translocation of 3C protease to carry out transcription inhibition in the nucleus. The 3CD polyprotein of poliovirus consists of the precursor of both the 3C protease (3Cpro) and the 3D RNA polymerase. 3CD undergoes proteolysis, which leads to localization in the nucleus. “The 3C protein, being of unknown function, is a product of 3CD cleavage by 2Apro”. Poliovirus is also involved in the cleavage of eIF4E (Eukaryotic translation initiation factor 4E). eIF4E is a protein involved in directing Eurkaryotic ribosomes in cap dependent translation. The proteolytic cleavage of eIF4E disables the host from carrying out cap dependent translation.
Coxsackievirus belongs to the Picornaviridae family and Enterovirus genus. Coxsackievirus is shed through stool and bodily fluids and is prevalent in children but can infection occur in adults. Symptoms for coxsackievirus are fever, malaise, rash and blisters. Coxsackievirus primarily infects mucosal and epithelial membranes. 3C proteinase activity in coxsackievirus causes apoptosis in
Picornain 3C