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==Location and Functions==
==Location and Functions==
ZIP9 [[Flux (biology)|influxes]] [[zinc ions]] into the [[cytosol]] and its gene is [[Gene expression|expressed]] almost in every [[Tissue (biology)|tissue]] of human body. <ref name="pmid25014355" /> The [[Subcellular location|sub-cellular location]] of ZIP9 is in [[Plasma membrane|plasma]], [[Nucleus biology|nucleus]], [[endoplasmic reticulum]] and [[mitochondrial membrane]].<ref name="pmid25014355" /> One of the responsibilities of ZIP9 is the [[homeostasis]] of [[zinc]] in the [[Secretory Pathway Ca²⁺ ATPase|secretory pathway]], during which this protein stays within the Trans [[Golgi apparatus|Golgi]] Network regardless of the change in the [[Concentration|concentrations]] of zinc.<ref name=":2" />
ZIP9 [[Flux (biology)|influxes]] [[zinc ions]] into the [[cytosol]] and its gene is [[Gene expression|expressed]] almost in every [[Tissue (biology)|tissue]] of human body. <ref name="pmid25014355" /> The [[Subcellular location|sub-cellular location]] of ZIP9 is in [[Plasma membrane|plasma]], [[Nucleus biology|nucleus]], [[endoplasmic reticulum]] and [[mitochondrial membrane]].<ref name="pmid25014355" /> One of the responsibilities of ZIP9 is the [[homeostasis]] of [[zinc]] in the [[Secretory Pathway Ca²⁺ ATPase|secretory pathway]], during which this protein stays within the Trans [[Golgi apparatus|Golgi]] Network regardless of the change in the [[Concentration|concentrations]] of zinc.<ref name=":2" />
[[File:Fphar-05-00033-g002.jpg|thumb|254x254px|The image illustrates the location of different zinc transporters in a cell, including ZIP9, which is located at Golgi here.<ref>{{Cite journal|last=Zhao|first=Lu|last2=Xia|first2=Zhidan|last3=Wang|first3=Fudi|date=2014|title=Zebrafish in the sea of mineral (iron, zinc, and copper) metabolism|url=https://www.frontiersin.org/articles/10.3389/fphar.2014.00033/full|journal=Frontiers in Pharmacology|language=English|volume=5|doi=10.3389/fphar.2014.00033|issn=1663-9812}}</ref>|none]]In contrast to [[Testosterone (medication)|testosterone]], which has high [[affinity (pharmacology)|affinity]] for ZIP9 with a [[Dissociation constant|K<sub>d</sub> of 14&nbsp;nM]], the other [[endogenous]] [[androgen]]s [[dihydrotestosterone]] (DHT) and [[androstenedione]] show low [[Affinity (chemistry)|affinity]] for the receptor with less than 1% of that of testosterone, although DHT is still effective in activating the [[Receptor (biochemistry)|receptor]] at sufficiently high concentrations.<ref name="pmid28479083" /> Moreover, the [[synthetic compound|synthetic]] androgens [[mibolerone]] and [[metribolone]] (R-1881), the endogenous androgen [[11-Ketotestosterone|11-ketotestoterone]], and the other [[steroid hormone]]s [[estradiol]] and [[cortisol]] are all ineffective competitors for the receptor.<ref name="pmid28479083" /> As such, [[mibolerone]] and [[metribolone]] could potentially be employed to differentiate between [[androgen receptor]]- and ZIP9-mediated responses of testosterone.<ref name="pmid28479083" />
[[File:Fphar-05-00033-g002.jpg|thumb|254x254px|The image illustrates the location of different zinc transporters in a cell, including ZIP9, which is located at Golgi here.<ref name="pmid24639652">{{cite journal | vauthors = Zhao L, Xia Z, Wang F | title = Zebrafish in the sea of mineral (iron, zinc, and copper) metabolism | journal = Frontiers in Pharmacology | volume = 5 | issue = | pages = 33 | year = 2014 | pmid = 24639652 | pmc = 3944790 | doi = 10.3389/fphar.2014.00033 | url = }}</ref>|none]]In contrast to [[Testosterone (medication)|testosterone]], which has high [[affinity (pharmacology)|affinity]] for ZIP9 with a [[Dissociation constant|K<sub>d</sub> of 14&nbsp;nM]], the other [[endogenous]] [[androgen]]s [[dihydrotestosterone]] (DHT) and [[androstenedione]] show low [[Affinity (chemistry)|affinity]] for the receptor with less than 1% of that of testosterone, although DHT is still effective in activating the [[Receptor (biochemistry)|receptor]] at sufficiently high concentrations.<ref name="pmid28479083" /> Moreover, the [[synthetic compound|synthetic]] androgens [[mibolerone]] and [[metribolone]] (R-1881), the endogenous androgen [[11-Ketotestosterone|11-ketotestoterone]], and the other [[steroid hormone]]s [[estradiol]] and [[cortisol]] are all ineffective competitors for the receptor.<ref name="pmid28479083" /> As such, [[mibolerone]] and [[metribolone]] could potentially be employed to differentiate between [[androgen receptor]]- and ZIP9-mediated responses of testosterone.<ref name="pmid28479083" />


==Isoforms and Sizes==
==Isoforms and Sizes==

Revision as of 19:12, 12 October 2017

SLC39A9
Identifiers
AliasesSLC39A9, ZIP-9, ZIP9, solute carrier family 39 member 9
External IDsMGI: 1914820; HomoloGene: 6935; GeneCards: SLC39A9; OMA:SLC39A9 - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_026244

RefSeq (protein)

NP_080520

Location (UCSC)Chr 14: 69.4 – 69.46 MbChr 12: 80.69 – 80.73 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Zrt- and Irt-like protein 9 (ZIP9), also known as solute-linked carrier family 39 member 9 (SLC39A9), is a protein which is encoded by the SLC39A9 gene.[5] This protein is the 9th member out of 14 ZIP family proteins, which is a membrane androgen receptor (mAR) coupled to G proteins, and also classified as a zinc transporter protein.[5][6][7][8] ZIP family proteins are known by their function which is transporting zinc metal from the extracellular environment into the cells through cell membrane and via selective transport.[6]

Classification and Nomenclature

Mammalian cells have two major groups of zinc transporter proteins; the ones that export zinc from the cytoplasm to the extracellular space (efflux), which are called ZnT (SLC30 family) , and ZIP (SLC39 family) proteins whose functions are in the opposite direction (influx).[9] ZIP family proteins are named as Zrt- and Irt-like proteins because of their similarities to Zrt and Irt proteins which are respectively zinc and iron -regulated transporter proteins in yeast and Arabidopsis that were discovered earlier than ZIP and ZnT proteins.[9] ZIP family is consisted of four subfamilies (I, II, LIV-1, and gufA), and ZIP9 is the only member of subfamily I.[10]

Protein Structure

Unlike other ZIP subfamilies that are consisted of 8 transmembrane (TM) domains with an extracellular C-terminal, ZIP9 is consisted of a 7 TM structure with an intracellular C-terminus.[7] ZIP9 is shorter than other ZIP proteins, and only has about 307 amino acids within its structure, however, like other ZIP proteins, between its domains III and IV, within the intracellular loop, it contains histidine-rich clusters.[7] ZIP9 and other ZIP proteins have polar or charged amino acids in their TM domains which probably play important roles in making ion transfer channels and therefore in importing zinc ions into cytoplasm.[11]

Location and Functions

ZIP9 influxes zinc ions into the cytosol and its gene is expressed almost in every tissue of human body. [8] The sub-cellular location of ZIP9 is in plasma, nucleus, endoplasmic reticulum and mitochondrial membrane.[8] One of the responsibilities of ZIP9 is the homeostasis of zinc in the secretory pathway, during which this protein stays within the Trans Golgi Network regardless of the change in the concentrations of zinc.[10]

The image illustrates the location of different zinc transporters in a cell, including ZIP9, which is located at Golgi here.[12]

In contrast to testosterone, which has high affinity for ZIP9 with a Kd of 14 nM, the other endogenous androgens dihydrotestosterone (DHT) and androstenedione show low affinity for the receptor with less than 1% of that of testosterone, although DHT is still effective in activating the receptor at sufficiently high concentrations.[5] Moreover, the synthetic androgens mibolerone and metribolone (R-1881), the endogenous androgen 11-ketotestoterone, and the other steroid hormones estradiol and cortisol are all ineffective competitors for the receptor.[5] As such, mibolerone and metribolone could potentially be employed to differentiate between androgen receptor- and ZIP9-mediated responses of testosterone.[5]

Isoforms and Sizes

ZIP9 can be present as 3 different isoforms in human cells. The canonical isoform of this protein has a length of 307 amino acids, with a molecular mass of 32,251Da. In the second isoform, amino acids 135-157 are missing, so its length and molecular weight are respectively reduced to 284 amino acids and 29,931Da. In the third isoform the amino acids 233-307 are missing, so the isoform only has 232 amino acids and its molecular mass is 24,626 Da. Additionally, the last amino acid of isoform 3, which is usually serine, is replaced with aspartic acid.[13]

ZIP9 Isoforms and Sizes[13]
Isoform number of amino acids size (Da) transformation missing amino acids
isoform 1 307 32251 N/A N/A
isoform 2 284 29931 N/A 135-157
isoform 3 232 24626 S -----> D 233-307

Discovery

ZIP9 membrane androgen receptor was first discovered in Atlantic croaker (Micropogonias undulatus) brain, ovary and testicular tissues and named "AR2" in 1999, together with another androgen receptor which was found only in brain tissue, and it was named "AR1" in that time.[14] AR1 and AR2 were first thought to be nuclear androgen receptors (nAR), however, further studies on their biochemical and functional features in 2003 illustrated that they were involved in non-genomic mechanisms in the plasma membrane of the cells and were membrane androgen receptors.[15] In 2005, the similarities between the nucleotide and amino acid sequences of AR2 and ZIP family proteins were discovered in other vertebrates, suggesting that AR2 is from this family of proteins.[11] A study in 2014 utilised the latest research technologies to clone and express a particular cDNA of the female Atlantic croaker ovaries, which encoded a protein showing the characteristics of the canonical isoform of ZIP9, as a novel membrane androgen receptor(mAR).[7]

Clinical significance

Zinc homeostasis is very important in human health, because zinc is present in the structure of some proteins like zinc-dependent metalloenzymes and zinc-finger-containing transcriptional factors.[16] As a result, any dysfunction of zinc transporter proteins can be harmful for the cells, and some of them are associated with different cancers, diabetes and inflammation.[16] For instance, through activation of ZIP9, testosterone has been found to increase intracellular zinc levels in breast cancer, prostate cancer, and ovarian follicle cells and to induce apoptosis in these cells, an action which may be mediated partially or fully by increased zinc concentrations.[5][17]

Cancer

Breast cancer

Breast cancer

Prostate cancer

Prostate cancer

Brain cancer

Brain Cancer

Diabetes

See also

References

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000029364Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000048833Ensembl, 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 Thomas P, Converse A, Berg HA (May 2017). "ZIP9, a novel membrane androgen receptor and zinc transporter protein". General and Comparative Endocrinology. doi:10.1016/j.ygcen.2017.04.016. PMID 28479083.
  6. ^ a b Eide DJ (February 2004). "The SLC39 family of metal ion transporters". Pflugers Archiv. 447 (5): 796–800. doi:10.1007/s00424-003-1074-3. PMID 12748861.
  7. ^ a b c d Berg AH, Rice CD, Rahman MS, Dong J, Thomas P (November 2014). "Identification and characterization of membrane androgen receptors in the ZIP9 zinc transporter subfamily: I. Discovery in female atlantic croaker and evidence ZIP9 mediates testosterone-induced apoptosis of ovarian follicle cells". Endocrinology. 155 (11): 4237–49. doi:10.1210/en.2014-1198. PMC 4197986. PMID 25014354.
  8. ^ a b c Thomas P, Pang Y, Dong J, Berg AH (November 2014). "Identification and characterization of membrane androgen receptors in the ZIP9 zinc transporter subfamily: II. Role of human ZIP9 in testosterone-induced prostate and breast cancer cell apoptosis". Endocrinology. 155 (11): 4250–65. doi:10.1210/en.2014-1201. PMC 4197988. PMID 25014355.
  9. ^ a b Lichten LA, Cousins RJ (2009-07-22). "Mammalian zinc transporters: nutritional and physiologic regulation". Annual Review of Nutrition. 29 (1): 153–76. doi:10.1146/annurev-nutr-033009-083312. PMID 19400752.
  10. ^ a b Matsuura W, Yamazaki T, Yamaguchi-Iwai Y, Masuda S, Nagao M, Andrews GK, Kambe T (May 2009). "SLC39A9 (ZIP9) regulates zinc homeostasis in the secretory pathway: characterization of the ZIP subfamily I protein in vertebrate cells". Bioscience, Biotechnology, and Biochemistry. 73 (5): 1142–8. doi:10.1271/bbb.80910. PMID 19420709.
  11. ^ a b Eide D.J. (2005) The Zip Family of Zinc Transporters. In: Iuchi S., Kuldell N. (eds) Zinc Finger Proteins. Molecular Biology Intelligence Unit. Springer, Boston, MA doi: https://doi.org/10.1007/0-387-27421-9_35
  12. ^ Zhao L, Xia Z, Wang F (2014). "Zebrafish in the sea of mineral (iron, zinc, and copper) metabolism". Frontiers in Pharmacology. 5: 33. doi:10.3389/fphar.2014.00033. PMC 3944790. PMID 24639652.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  13. ^ a b Universal protein resource accession number Q9NUM3 at UniProt.
  14. ^ Sperry, Todd S.; Thomas, Peter (1999-04-01). "Characterization of Two Nuclear Androgen Receptors in Atlantic Croaker: Comparison of Their Biochemical Properties and Binding Specificities". Endocrinology. 140 (4): 1602–1611. doi:10.1210/endo.140.4.6631. ISSN 0013-7227.
  15. ^ Braun, Alyssa M.; Thomas, Peter (2003-11-01). "Androgens Inhibit Estradiol-17β Synthesis in Atlantic Croaker (Micropogonias undulatus) Ovaries by a Nongenomic Mechanism Initiated at the Cell Surface". Biology of Reproduction. 69 (5): 1642–1650. doi:10.1095/biolreprod.103.015479. ISSN 0006-3363.
  16. ^ a b Taniguchi M, Fukunaka A, Hagihara M, Watanabe K, Kamino S, Kambe T, Enomoto S, Hiromura M (2013). "Essential role of the zinc transporter ZIP9/SLC39A9 in regulating the activations of Akt and Erk in B-cell receptor signaling pathway in DT40 cells". Plos One. 8 (3): e58022. doi:10.1371/journal.pone.0058022. PMC 3591455. PMID 23505453.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  17. ^ Pascal LE, Wang Z (2014). "Unzipping androgen action through ZIP9: a novel membrane androgen receptor". Endocrinology. 155 (11): 4120–3. doi:10.1210/en.2014-1749. PMID 25325426.