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Virion infectivity factor



Human immunodeficiency virus type 1 group M subtype C (isolate 92BR025) (HIV-1)
Reviewed-Annotation score: Annotation score: 3 out of 5-Experimental evidence at transcript leveli


Counteracts the innate antiviral activity of human APOBEC3F and APOBEC3G. Forms a complex with host APOBEC3F and APOBEC3G thus preventing the entry of these lethally hypermutating enzymes into progeny virions. Recruits an active E3 ubiquitin ligase complex composed of elongin BC, CUL5, and RBX2 to induce polyubiquitination of APOBEC3G and APOBEC3F. In turn, they are directed to the 26S proteasome for degradation. Vif interaction with APOBEC3G also blocks its cytidine deaminase activity in a proteasome-independent manner, suggesting a dual inhibitory mechanism. May interact directly with APOBEC3G mRNA in order to inhibit its translation. Seems to play a role in viral morphology by affecting the stability of the viral nucleoprotein core. Finally, Vif also contributes to the G2 cell cycle arrest observed in HIV infected cells (By similarity).By similarity


Required for replication in 'nonpermissive' cells, including primary T-cells, macrophages and certain T-cell lines, but is dispensable for replication in 'permissive' cell lines, such as 293T cells. In nonpermissive cells, Vif-defective viruses can produce virions, but they fail to complete reverse transcription and cannot successfully infect new cells (By similarity).By similarity
Vif-defective viruses show catastrophic failure in reverse transcription due to APOBEC-induced mutations that initiate a DNA base repair pathway and compromise the structural integrity of the ssDNA. In the absence of Vif, the virion is morphologically abnormal (By similarity).By similarity
HIV-1 lineages are divided in three main groups, M (for Major), O (for Outlier), and N (for New, or Non-M, Non-O). The vast majority of strains found worldwide belong to the group M. Group O seems to be endemic to and largely confined to Cameroon and neighboring countries in West Central Africa, where these viruses represent a small minority of HIV-1 strains. The group N is represented by a limited number of isolates from Cameroonian persons. The group M is further subdivided in 9 clades or subtypes (A to D, F to H, J and K).

GO - Molecular functioni

GO - Biological processi


Molecular functionRNA-binding
Biological processHost-virus interaction, Ubl conjugation pathway

Names & Taxonomyi

Protein namesi
Recommended name:
Virion infectivity factor
Short name:
Alternative name(s):
SOR protein
Cleaved into the following 2 chains:
Gene namesi
OrganismiHuman immunodeficiency virus type 1 group M subtype C (isolate 92BR025) (HIV-1)
Taxonomic identifieri388812 [NCBI]
Taxonomic lineageiVirusesRetro-transcribing virusesRetroviridaeOrthoretrovirinaeLentivirusPrimate lentivirus group
Virus hostiHomo sapiens (Human) [TaxID: 9606]
  • UP000007686 Componenti: Chromosome

Subcellular locationi

  • Host cytoplasm By similarity
  • Host cell membrane By similarity; Peripheral membrane protein By similarity; Cytoplasmic side By similarity
  • Virion By similarity

  • Note: In the cytoplasm, seems to colocalize with intermediate filament vimentin. A fraction is associated with the cytoplasmic side of cellular membranes, presumably via the interaction with Pr55Gag precursor. Incorporated in virions at a ratio of approximately 7 to 20 molecules per virion (By similarity).By similarity

GO - Cellular componenti

Keywords - Cellular componenti

Host cell membrane, Host cytoplasm, Host membrane, Membrane, Virion

Pathology & Biotechi

Keywords - Diseasei


PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00002451071 – 192Virion infectivity factorBy similarityAdd BLAST192
ChainiPRO_00002451081 – 150p17By similarityAdd BLAST150
ChainiPRO_0000245109151 – 192p7By similarityAdd BLAST42

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei96Phosphothreonine; by host MAP4K1By similarity1
Modified residuei144Phosphoserine; by hostBy similarity1
Modified residuei165Phosphoserine; by host MAP4K1By similarity1
Modified residuei188Phosphothreonine; by hostBy similarity1

Post-translational modificationi

Processed in virion by the viral protease.By similarity
Highly phosphorylated on serine and threonine residues. Thr-96 and Ser-165 are phosphorylated by the mitogen activated kinase MAP4K1. As the HIV-1 replication can be activated by stress and mitogens, these phosphorylations could be involved in this process. Ser-144 phosphorylation may inhibit elongin BC complex binding (By similarity).By similarity
Polyubiquitinated and degraded by the proteasome in the presence of APOBEC3G.By similarity


Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sitei150 – 151Cleavage in virion (by viral protease)By similarity2

Keywords - PTMi

Phosphoprotein, Ubl conjugation



Expressed late during infection in a Rev-dependent manner.


Subunit structurei

Homomultimer; in vitro and presumably in vivo. Interacts with viral RNA and Pr55Gag precursor; these interactions mediate Vif incorporation into the virion. Interacts with the viral reverse transcriptase. Interacts with human APOBEC3F and APOBEC3G. Interacts with host UBCE7IP1 isoform 3/ZIN and possibly with SAT. Interacts with host tyrosine kinases HCK and FYN; these interactions may decrease level of phosphorylated APOBEC3G incorporation into virions. Interacts with host ABCE1; this interaction may play a role in protecting viral RNA from damage during viral assembly. Forms an E3 ligase complex by interacting with human CUL5 and elongin BC complex (ELOB and ELOC). Interacts with host MDM2; this interaction targets Vif for degradation by the proteasome (By similarity).By similarity


3D structure databases


Family & Domainsi


Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni14 – 17Interaction with host APOBEC3F; F1-boxBy similarity4
Regioni40 – 44Interaction with host APOBEC3G; G-boxBy similarity5
Regioni54 – 72Interaction with host APOBEC3F and APOBEC3G; FG-boxBy similarityAdd BLAST19
Regioni74 – 79Interaction with host APOBEC3F; F2-boxBy similarity6
Regioni75 – 114RNA-bindingSequence analysisAdd BLAST40
Regioni151 – 164MultimerizationBy similarityAdd BLAST14
Regioni171 – 172Membrane associationBy similarity2


Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi108 – 139HCCH motifBy similarityAdd BLAST32
Motifi144 – 153BC-box-like motifBy similarity10


The BC-like-box motif mediates the interaction with elongin BC complex.By similarity
The HCCH motif (H-x5-C-x(18)-C-x5-H) mediates the interaction with CUL5.By similarity

Sequence similaritiesi

Phylogenomic databases


Family and domain databases

InterProiView protein in InterPro
IPR000475. Viral_infect.
PfamiView protein in Pfam
PF00559. Vif. 1 hit.


Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

O12159-1 [UniParc]FASTAAdd to basket

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Mass (Da):22,762
Last modified:July 1, 1997 - v1

Sequence databases

Select the link destinations:
Links Updated
U52953 Genomic DNA. Translation: AAB61127.1.

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.

Entry informationi

Entry nameiVIF_HV192
AccessioniPrimary (citable) accession number: O12159
Entry historyiIntegrated into UniProtKB/Swiss-Prot: July 11, 2006
Last sequence update: July 1, 1997
Last modified: March 15, 2017
This is version 75 of the entry and version 1 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programViral Protein Annotation Program


Keywords - Technical termi

Complete proteome


  1. SIMILARITY comments
    Index of protein domains and families