P21443 (ENV_FLVC6) Reviewed, UniProtKB/Swiss-Prot
Last modified October 16, 2013. Version 81. History...
Names and origin
|Protein names||Recommended name:|
|Organism||Feline leukemia virus (isolate CFE-6)|
|Taxonomic identifier||11922 [NCBI]|
|Taxonomic lineage||Viruses › Retro-transcribing viruses › Retroviridae › Orthoretrovirinae › Gammaretrovirus ›|
|Virus host||Felidae (cat family) [TaxID: 9681]|
|Sequence length||668 AA.|
|Sequence processing||The displayed sequence is further processed into a mature form.|
|Protein existence||Inferred from homology|
General annotation (Comments)
The surface protein (SU) attaches the virus to the host cell by binding to its receptor. This interaction triggers the refolding of the transmembrane protein (TM) and is thought to activate its fusogenic potential by unmasking its fusion peptide. Fusion occurs at the host cell plasma membrane By similarity.
The transmembrane protein (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm By similarity.
The mature envelope protein (Env) consists of a trimer of SU-TM heterodimers attached by a labile interchain disulfide bond By similarity.
Surface protein: Virion membrane; Peripheral membrane protein. Host cell membrane; Peripheral membrane protein By similarity. Note: The surface protein is not anchored to the viral envelope, but associates with the extravirion surface through its binding to TM. Both proteins are thought to be concentrated at the site of budding and incorporated into the virions possibly by contacts between the cytoplasmic tail of Env and the N-terminus of Gag By similarity.
The 17 amino acids long immunosuppressive region is present in many retroviral envelope proteins. Synthetic peptides derived from this relatively conserved sequence inhibit immune function in vitro and in vivo By similarity.
The YXXL motif is involved in determining the exact site of viral release at the surface of infected mononuclear cells and promotes endocytosis.
Specific enzymatic cleavages in vivo yield mature proteins. Envelope glycoproteins are synthesized as a inactive precursor that is N-glycosylated and processed likely by host cell furin or by a furin-like protease in the Golgi to yield the mature SU and TM proteins. The cleavage site between SU and TM requires the minimal sequence [KR]-X-[KR]-R. The R-peptide is released from the C-terminus of the cytoplasmic tail of the TM protein upon particle formation as a result of proteolytic cleavage by the viral protease. Cleavage of this peptide is required for TM to become fusogenic By similarity.
The CXXC motif is highly conserved across a broad range of retroviral envelope proteins. It is thought to participate in the formation of a labile disulfide bond possibly with the CX6CC motif present in the transmembrane protein. Isomerization of the intersubunit disulfide bond to an SU intrachain disulfide bond is thought to occur upon receptor recognition in order to allow membrane fusion By similarity.
The transmembrane protein is palmitoylated By similarity.
The R-peptide is palmitoylated By similarity.
Sequence annotation (Features)
|Feature key||Position(s)||Length||Description||Graphical view||Feature identifier|
|Signal peptide||1 – 34||34||Potential|
|Chain||35 – 668||634||Envelope glycoprotein||PRO_0000239561|
|Chain||35 – 465||431||Surface protein By similarity||PRO_0000040706|
|Chain||466 – 644||179||Transmembrane protein By similarity||PRO_0000040707|
|Peptide||645 – 668||24||R-peptide By similarity||PRO_0000239562|
|Topological domain||35 – 605||571||Extracellular Potential|
|Transmembrane||606 – 626||21||Helical; Potential|
|Topological domain||627 – 668||42||Cytoplasmic Potential|
|Region||467 – 487||21||Fusion peptide Potential|
|Region||533 – 549||17||Immunosuppression By similarity|
|Coiled coil||495 – 544||50||Potential|
|Coiled coil||554 – 590||37||Potential|
|Motif||332 – 335||4||CXXC|
|Motif||550 – 558||9||CX6CC|
|Motif||650 – 653||4||YXXL motif; contains endocytosis signal By similarity|
|Site||465 – 466||2||Cleavage; by host By similarity|
|Site||644 – 645||2||Cleavage; by viral protease By similarity|
Amino acid modifications
|Lipidation||625||1||S-palmitoyl cysteine; by host By similarity|
|Glycosylation||43||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||58||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||286||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||322||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||327||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||351||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||354||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||394||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||410||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||430||1||N-linked (GlcNAc...); by host Potential|
|Disulfide bond||115 ↔ 132||By similarity|
|Disulfide bond||124 ↔ 137||By similarity|
|Disulfide bond||332 ↔ 558||Interchain (between SU and TM chains, or C-335 with C-558); alternate By similarity|
|Disulfide bond||332 ↔ 335||Alternate By similarity|
|Disulfide bond||550 ↔ 557||By similarity|
|M25425 Genomic DNA. Translation: AAA30809.1.|
3D structure databases
|SMR||P21443. Positions 38-242, 510-562. |
Protocols and materials databases
Family and domain databases
|Gene3D||3.90.310.10. 1 hit. |
|InterPro||IPR008981. FMuLV_rcpt-bd. |
|PANTHER||PTHR10424. PTHR10424. 1 hit. |
|Pfam||PF00429. TLV_coat. 1 hit. |
|SUPFAM||SSF49830. SSF49830. 1 hit. |
|Accession||Primary (citable) accession number: P21443|
|Entry status||Reviewed (UniProtKB/Swiss-Prot)|
|Annotation program||Viral Protein Annotation Program|