ERVFRD-1

Domain

Contains the CKS-17 immunosuppressive domain present in many retroviral envelope proteins. As a synthetic peptide, it inhibits immune function in vitro and in vivo (By similarity).

Function

This endogenous retroviral envelope protein has retained its original fusogenic properties and participates in trophoblast fusion and the formation of a syncytium during placenta morphogenesis. The interaction with MFSD2A is apparently important for this process (PubMed:18988732).

Endogenous envelope proteins may have kept, lost or modified their original function during evolution but this one can still make pseudotypes with MLV, HIV-1 or SIV-1 virions and confer infectivity. Retroviral envelope proteins mediate receptor recognition and membrane fusion during early infection. The surface protein mediates receptor recognition, while the transmembrane protein anchors the envelope heterodimer to the viral membrane through one transmembrane domain. The other hydrophobic domain, called fusion peptide, mediates fusion of the viral membrane with the target cell membrane (PubMed:14694139).

Post-translational modifications

Specific enzymatic cleavages in vivo yield the mature SU and TM proteins.

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).

Sequence Similarities

Belongs to the gamma type-C retroviral envelope protein family. HERV class-I FRD env subfamily.

Tissue Specificity

Expressed at higher level in placenta. Expressed at lower level in adrenal, bone marrow, brain, breast, colon, kidney, lung, ovary, peripheral blood lymphocytes, prostate, skin, spleen, testis, thymus, thyroid, trachea.

Cellular localization

• Virion
• Surface protein
• Cell membrane
• Peripheral membrane protein
• The surface protein is not anchored to the membrane, but localizes to the extracellular surface through its binding to TM.
• Transmembrane protein
• Cell membrane
• Single-pass membrane protein

Alternative names

ERVFRDE1, UNQ6191/PRO20218, ERVFRD-1, Syncytin-2, Endogenous retrovirus group FRD member 1, Envelope polyprotein, HERV-FRD, HERV-FRD_6p24.1 provirus ancestral Env polyprotein

Database links

swissprot:P60508 swissprot:Q9N2J8 swissprot:Q902F8 swissprot:Q9NX77 swissprot:Q902F9 swissprot:Q14264 swissprot:Q9N2J9 swissprot:Q9N2K0 swissprot:Q9UQF0 swissprot:Q9UKH3 entrezGene:2086 entrezGene:30816 entrezGene:405754 swissprot:Q69384 omim:610524 swissprot:O71037 swissprot:O42043 swissprot:P10267 swissprot:P61550 swissprot:P61565 swissprot:P61566 swissprot:P61567 swissprot:P61570 swissprot:P60507 swissprot:Q96L62