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. 2020 Sep 8;88:106980. doi: 10.1016/j.intimp.2020.106980

Table 1.

Different proteins of SARS-CoV2 and their function in virus life cycle (replication, assembly, and pathogenesis).

SARS-CoV2 proteins Functions
  • 1.

    ORF1ab

 Expressed as polyprotein comprising of 16 Nsps (mentioned below)
  • 2.

    Nsp1

 Binds to host 40S ribosome and promotes host cell RNA degradation, Blocks RIG-1-dependent antiviral immune response
  • 3.

    Nsp2

 Binds to host cell prohibitin 1 and 2 (PHB1 and PHB2) to disrupt host cell environment
  • 4.

    Nsp3 (a papain-like protease)
  • 1.

    Releases Nsp1, Nsp2, and Nsp3 from the N-terminal region of polyproteins 1a and 1ab from CoVs for virus replication

  • 2.

    Nsp3 interacts with TBK1 to inhibit potent type-1 IFN-based antiviral immune response
  • 5.

    Nsp4

 Binds to Nsp3 and helps in virus replication
  • 6.

    Nsp5

 Cleaves at 11 sites of (3C-like proteinase) NSP polyprotein
  • 7.

    Nsp6
  • 1.

    Autophagosome formation facilitating assembly of replicase proteins

  • 2.

    Prevents autophagosome and lysosome fusion to form autophagolysosome or autolysosomes to escape lysosomal degradation
  • 8.

    Nsp7

 Forms complex with Nsp8 and Nsp12 to yield NSP8 RNA polymerase activity
  • 9.

    Nsp8
  • 1.

    Forms complex with Nsp7 and Nsp12 to act as RNA polymerase

  • 2.

    Binds to TRIM59 to inhibit pro-inflammatory immune response

  • 3.

    Nsp8 binds to LC3-II to get into autophagosome and then to autolysosomes for virus replication
  • 10.

    Nsp9

 Interacts with DEAD-box RNA helicase 5 (DDX5) of host cell to increase viral replication
  • 11.

    Nsp10

 Activates NSP14 and NSP16, which are methyltransferases
  • 12.

    Nsp11

 Unknown
  • 13.

    Nsp12

 RNA-dependent RNA polymerase, forms complex with Nsp7 and Nsp8
  • 14.

    Nsp13
  • 1.

    Acts as an Helicase to unwind the duplex RNA, Nsp12 binding enhances its helicase activity

  • 2.

    Also exerts 5′-trophosphatase activity for introducing 5′-terminal cap in the viral RNA

  • 3.

    Blocks type 1 IFN release via binding to TBK1 and TBKBP1

  • 4.

    Interacts with TLE3 and TLE4 to inhibit IL-6 and IL-12 release
  • 15.

    Nsp4

 Exerts 3′-5′ exoribonucleaseactivity and N7-methyltransferase activity
  • 16.

    Nsp15
  • 1.

    Acts as an endoribonuclease that cleaves RNA at uridylates at the 3-position to form a 2-3′cyclic phosphodiester product by using manganese (Mn) as a cofactor

  • 2.

    Targets specifically, viral polyuridine sequences to prevent the virus recognition by the host innate immune system

  • 3.

    Degrades viral RNA to escape from cytosolic or endosomal PRR-mediated recognition

  • 4.

    Binds to RNF41 (RING finger protein 41)/Nrdp1 (an E3 ubiquitin-protein ligase) to inhibit IRF-3-dependent Type 1 IFN release

  • 5.

    Binds to neuregulin receptor degradation protein 1 (Nrdp1, a E3 ubiquitin-protein ligase) to aggravate TLR signaling-dependent pro-inflammatory cytokines release
  • 17.

    Nsp16

 Acts as a 2′‑O‑Ribose‑Methyltransferase and methylates the 2′-hydroxy group of adenine using S-adenosylmethionine (SAM) as the methyl source
  • 18.

    Spike or S protein

 Recognizes and binds to ACE2 receptor of the host cells to enter for replication and productive infection
  • 19.

    ORF3a
  • 1.

    Interacts with TRAF3 to activate ASC for caspase-1 activation required for NLRP3 inflammasome to release pro-inflammatory cytokines (IL-1β and IL-18)

  • 2.

    Binds to TRIM59 and inhibits NF-κB and ISRE-dependent antiviral immune response
  • 20.

    Envelope or E protein
  • 1.

    Can for ion channel

  • 2.

    Virus assembly

  • 3.

    Virion release

  • 4.

    Infection pathogenesis
  • 21.

    Membrane or M protein
  • 1.

    Virus assembly

  • 2.

    May induce apoptosis among infected host cells

  • 3.

    Interacts with N protein to for capsomeres to form capsid around viral RNA
  • 22.

    ORF6

 Interacts with Nsp8 to promote RNA polymerase activity
  • 23.

    ORF7a

 Accessory protein acting as a type 1 trans-membrane protein
  • 24.

    ORF7b

 Accessory protein, localizes to Golgi apparatus, may help in virus assembly
  • 25.

    ORF8

 Comprises of ORF8a and ORF8b, binds to IRF association domain (IAD) of IRF3 via ORF8b to inhibit type 1 IFNs release
  • 26.

    ORF9c

 Interacts with NLRX1 and inhibits RLR and NLRP3-mediated innate immune response, but promotes TLR signaling-dependent pro-inflammatory immune response
  • 27.

    ORF10

 Unknown
  • 28.

    Nucleocapsid or N protein
  • 1.

    Binds to viral RNA to increase its stability

  • 2.

    Antagonizes host antiviral RNAi

  • 3.

    Inhibits cyclin-dependent kinase (CDK) to block the S-phase progression of the cell cycle progression