P03394 (ENV_FRSFL) Reviewed, UniProtKB/Swiss-Prot
Last modified October 16, 2013. Version 89. History...
Names and origin
|Protein names||Recommended name:|
|Organism||Friend spleen focus-forming virus (strain Lilly-Steeves) (FSFFV)|
|Taxonomic identifier||355328 [NCBI]|
|Taxonomic lineage||Viruses › Retro-transcribing viruses › Retroviridae › Orthoretrovirinae › Gammaretrovirus › unclassified Gammaretrovirus ›|
|Virus host||Mus [TaxID: 10088]|
|Sequence length||409 AA.|
|Sequence processing||The displayed sequence is further processed into a mature form.|
|Protein existence||Inferred from homology|
General annotation (Comments)
This envelope-like membrane glycoprotein is responsible for ligand-independent activation of the erythropoietin receptor EPOR leading to the abnormally rapid proliferation of erythroid precursor cells. In the first stage of Friend disease, constitutive activation of EPOR by gp55 causes uncontrolled, polyclonal proliferation of infected erythroblasts, leading to polycythemia (massive increase in the number of mature red cells). Host susceptibility to SSFV-induced erythroblastosis depends on the expression of the truncated isoform of MST1R receptor tyrosine kinase (MST1R isoform sf-Stk). Interaction with SSFV gp 55 results in constitutive tyrosine phosphorylation and activation of MST1R isoform sf-Stk By similarity.
Homooligomer. Forms heterooligomers with mouse EPOR, probably via their respective transmembrane domains. Forms covalent heterodimers with mouse MST1R isoform sf-Stk, probably via disulfide bonds By similarity.
Host endoplasmic reticulum membrane; Single-pass type I membrane protein. Host cell membrane; Single-pass type I membrane protein. Virion membrane; Single-pass type I membrane protein. Note: The envelope-like membrane glycoprotein gp55 is defective in its transport to the cell surface and remains associated predominantly with the rough endoplasmic reticulum (RER) membrane. It is almost not incorporated into virions. Host cell surface expression appears to be a prerequisite for its leukemogenicity By similarity.
Compared to other gammaretroviruses which possess 2 envelope proteins (gp70 and p15E), gp55 corresponds to a gp70-p15E fusion protein with a deletion of a portion of p15E. It is encoded by the defective env gene of the virus.
The Friend murine leukemia virus complex induces a rapid and fatal erythroleukemia in adult mice. It is the replication-defective spleen focus-forming virus (SFFV) contained in this complex that causes foci of proliferating erythroid cells in spleens of infected mice. The second component is a replication competent Friend murine leukemia virus (F-MuLV) that serves as a helper virus for SFFV.
Sequence annotation (Features)
|Feature key||Position(s)||Length||Description||Graphical view||Feature identifier|
|Signal peptide||1 – 32||32||Potential|
|Chain||33 – 409||377||Glycoprotein 55||PRO_0000040720|
|Topological domain||33 – 384||352||Virion surface Potential|
|Transmembrane||385 – 405||21||Helical; Potential|
|Topological domain||406 – 409||4||Intravirion Potential|
|Compositional bias||229 – 278||50||Pro-rich|
Amino acid modifications
|Glycosylation||43||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||58||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||296||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||328||1||N-linked (GlcNAc...); by host Potential|
|Glycosylation||377||1||N-linked (GlcNAc...); by host Potential|
|||"Envelope gene of the Friend spleen focus-forming virus: deletion and insertions in 3' gp70/p15E-encoding region have resulted in unique features in the primary structure of its protein product."|
Wolff L., Scolnick E., Ruscetti S.
Proc. Natl. Acad. Sci. U.S.A. 80:4718-4722(1983) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
|V01552 Genomic DNA. Translation: CAA24793.1.|
|PIR||VCVW2S. A03994. |
3D structure databases
|SMR||P03394. Positions 38-229. |
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. 3 hits. |
|SUPFAM||SSF49830. SSF49830. 1 hit. |
|Accession||Primary (citable) accession number: P03394|
|Entry status||Reviewed (UniProtKB/Swiss-Prot)|
|Annotation program||Viral Protein Annotation Program|