VXN

Vexin is a protein encoded by "VXN" gene. "VXN" is found to be highly expressed in regions of the brain and spinal cord.
Gene.
Location.
"VXN" is found along the plus strand of chromosome 8. The entire gene is 58,522 bp long. "VXN" is flanked by alcohol dehydrogenase iron containing 1 and Myb proto-oncogene like 1.
Homology.
Paralogs.
No human paralogs for VXN have been identified
Orthologs.
Vexin is found in all classes of vertebrates, including mammals, birds, fish, reptiles and amphibians. 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. The gene has not been found in any plants, fungi or single celled organisms.
Homologous Domains.
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.
Splice Variants.
"VXN" does not have any alternative mRNA splice variants. The mature mRNA is approximately 3,741 base pairs in length and contains six exons.
Protein.
General Properties.
Vexin is 207 amino acids long, which equates to a molecular weight of 22.6 kdal. The isoelectric point of the protein is 10.42 which indicates the pH of the protein is basic. 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. The secondary and tertiary structure of this protein is not well known.
Composition.
Vexin is considered rich in arginine, and poor in phenylalanine compared to the composition of the average human protein. Vexin does contain several regions of positively charged runs and has a high concentration of basic amino acids.
Post-Translational Modifications.
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, sumolyation and initial methionine acetylation.
Subcellular Location.
 Vexin is predicted to be a nuclear protein, given the classical nuclear localization signal found at amino acids Lys191 to Lys193. Vexin does not contain any transmembrane domains or signal peptides suggesting that it is an intracellular protein.
Expression.
"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. 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. "VXN" is only expressed in infants and adults.
Regulation of Expression.
Promoter.
The promoter region of "VXN", GXP_80707, is approximately 1,044 bp in length. The promoter sequence begins at 66,492,708 bp and ends at 66,493,751 bp. There are several important transcription factors that are predicted to bind to the promoter sequence of "VXN". The most common transcription factors include; HMG box-containing protein 1, repressive glucocorticoid receptor, cAMP-responsive binding protein and Homeo domain factor Pbx-1.
Clinical Significance.
"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. It is predicted that "VXN" has ESR1 enhancer regions that become hypermethylated and promote acquired endocrine resistance in breast cancer.