Vexin is a protein encoded by VXN gene.[5] VXN is found to be highly expressed in regions of the brain and spinal cord.

VXN
Identifiers
AliasesVXN, chromosome 8 open reading frame 46, C8orf46, vexin
External IDsMGI: 1924232; HomoloGene: 17666; GeneCards: VXN; OMA:VXN - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_152765

NM_178399

RefSeq (protein)

NP_689978

NP_848486

Location (UCSC)Chr 8: 66.49 – 66.52 MbChr 1: 9.67 – 9.7 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Gene

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Location

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VXN is found along the plus strand of chromosome 8.[6] The entire gene is 58,522 bp long.[6] VXN is flanked by alcohol dehydrogenase iron containing 1 and Myb proto-oncogene like 1.[5]

 
Gene neighborhood of VXN along the forward strand of chromosome 8.

Homology

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Paralogs

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No human paralogs for VXN have been identified[5]

Orthologs

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Phylogentic tree of select orthologs of the gene VXN. Estimated date of divergence is shown.

Vexin is found in all classes of vertebrates, including mammals, birds, fish, reptiles and amphibians.[5] The most distant ortholog of VXN is in Callorhinchus milli, which diverged from the human version of the gene an estimated 482.9 million years ago.[7] The gene has not been found in any plants, fungi or single celled organisms.[5]

Homologous domains

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The N-terminus and C-terminus are highly conserved regions across both distant and close orthologs. The orthologs of vexin all show conservation of the SH3 protein domain family as well as a domain of unknown function (DUF4648).

mRNA

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Splice variants

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VXN does not have any alternative mRNA splice variants. The mature mRNA is approximately 3,741 base pairs in length and contains six exons.[6]

Protein

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General properties

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Location of the domain of unknown function and nuclear localization signal along vexin.

Vexin is 207 amino acids long, which equates to a molecular weight of 22.6 kdal.[6] The isoelectric point of the protein is 10.42 which indicates the pH of the protein is basic.[8] Vexin does contain a domain of unknown function (DUF4648) and is a part of the SH3 domain family, which is known to bind to proline-rich ligands.[5] The secondary and tertiary structure of this protein is not well known.

Composition

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Vexin is considered rich in arginine, and poor in phenylalanine compared to the composition of the average human protein.[8] Vexin does contain several regions of positively charged runs and has a high concentration of basic amino acids.[8]

Post-translational modifications

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Vexin is predicted to undergo several types of post translational modifications. With a high degree of certainty, it is predicted that vexin undergoes lysine glycation, O-glycosylation, serine, threonine and tyrosine phosphorylation, SUMOylation and initial methionine acetylation.[9]

Type of Modification Amino Acid Position Impact on Protein[10]
Glycation of Epsilon Amino Groups of Lysine Lys33, Lys41, Lys124, Lys152. Lys153, Lys193 Impairs enzymatic function of protein.
Initial Methionine Acetylation Met1 Mediates protein stability, sorting and localization.
O-glycosylation sites Ser25, Ser90, Ser97, Ser102, Ser113, Ser122, Ser126, Ser128 Ser130, Ser148, Ser194, Thr78, Thr101, Thr125, Thr134, Thr155 Regulates transcription and translation factors.
Phosphorylation sites Ser22, Ser25, Ser26, Ser34, Ser35, Ser97, Ser122, Ser126, Ser130, Ser194, Thr78, Thr83, Thr138, Tyr50, Tyr158, Tyr196 Regulates protein function, cell signaling and enzymatic functions of protein
SUMOylation sites Lys141, Lys195 Plays a role in nuclear-cytosolic transport, acts as binding site.

Subcellular location

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Conceptual translation of VXN depicts predicted post-translational modification sites.

Vexin is predicted to be a nuclear protein, given the classical nuclear localization signal found at amino acids Lys191 to Lys193.[9] Vexin does not contain any transmembrane domains or signal peptides suggesting that it is an intracellular protein.[9]

Expression

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Image from Allen Brain Atlas shows the areas of elevated expression of VXN in the brain.[11]

VXN has shown to be ubiquitously expressed in the body. The gene is expressed in 13 different types of tissue throughout the body, with the brain, spinal cord and nerves showing elevated expression of the gene.[12] Specifically, the isocortex and hippocampal formation areas of the brain show high levels of expression. In addition to healthy tissue, vexin is also found in several disease states. These disease states include chondrosarcoma, glioma, kidney tumors, liver tumors, and germ cell tumors.[12] VXN is only expressed in infants and adults.[12]

Clinical significance

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VXN has been associated with breast cancer in humans. The gene has been researched in connection with estrogen receptor 1- enhancer (ESR1), whose expression determines if a breast cancer patient receives endocrine therapy.[13] It is predicted that VXN has ESR1 enhancer regions that become hypermethylated and promote acquired endocrine resistance in breast cancer.[13]

References

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  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000169085Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000067879Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ a b c d e f "VXN vexin [ Homo sapiens (human) ]". National Center for Biotechnology Information. Retrieved 2021-01-06.
  6. ^ a b c d "VXN Gene - Vexin". GeneCards. Retrieved 2016-04-25.
  7. ^ "TimeTree :: The Timescale of Life". timetree.org. Retrieved 2016-05-09.
  8. ^ a b c "SDSC Biology Workbench".[permanent dead link]
  9. ^ a b c "ExPASy: SIB Bioinformatics Resource Portal - Home". expasy.org. Retrieved 2016-04-25.
  10. ^ "Overview of Post-Translational Modification". Thermo Fisher Scientific. Retrieved 2016-05-09.
  11. ^ "ISH Data :: Allen Brain Atlas: Developing Mouse Brain". developingmouse.brain-map.org. Retrieved 2016-05-09.
  12. ^ a b c "EST Profile - Hs.268869". National Center for Biotechnology Information. Retrieved 2016-05-09.
  13. ^ a b Stone A, Zotenko E, Locke WJ, Korbie D, Millar EK, Pidsley R, et al. (July 2015). "DNA methylation of oestrogen-regulated enhancers defines endocrine sensitivity in breast cancer". Nature Communications. 6: 7758. doi:10.1038/ncomms8758. PMC 4510968. PMID 26169690.

Further reading

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  NODES
Note 1