Zinc transporter protein

Zinc transporter proteins (Zrt), or simply zinc transporters, are membrane transport proteins of the solute carrier family which control the membrane transport of zinc and regulate its intracellular and cytoplasmic concentrations.^[1] They include two major groups: (1) the zinc transporter (ZnT) or solute carrier 30 (SLC30) family, which controls the efflux of zinc from the cytoplasm out of the cell and from the cytoplasm into vesicles; and (2) the zinc importer, Zrt- and Irt-like protein (ZIP), or solute carrier 39A (SLC39A) family, which controls the influx of zinc into the cytoplasm from outside the cell and from vesicles.^[1]

At least one zinc transporter, ZIP9, is also a G protein-coupled receptor and membrane androgen receptor.^[2]

Families

ZnT (SLC30)

Cation efflux (diffusion facilitator) protein
ZntB Transporter Protein Structure: The left side of the image shows the full-length ZntB protein structure, without the presence of zinc. The right side shows the cytoplasmic domain of the protein and the apparent conformation change undergone by the protein to accommodate zinc transport. The conformation change is believed to be necessary for zinc ion transport. The chlorine ions (illustrated as the orange circles) support the conclusion that a change in the electrostatics and pH are necessary for transport.[3][4]
Identifiers
Symbol	Cation_efflux
Pfam	PF01545
InterPro	IPR002524
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Members: ZnT1, ZnT2, ZnT3, ZnT4, ZnT5, ZnT6, ZnT7, ZnT8, ZnT9, ZnT10

Bacterial members of the family are known to increase tolerance to high salt concentrations.

ZntB Zinc Transporter Protein

Unlike some other zinc transporter proteins, the mechanism of how Zn²⁺ is transported via ZntB is not well understood. However, scientists have been able to speculate that the transport of Zn²⁺ is related to pH gradient and the electrostatics of the protein membrane.^[3][4]

ZIP (SLC39)

Zinc/iron permease
Identifiers
Symbol	ZIP
Pfam	PF02535
InterPro	IPR003689
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

ZIP1, ZIP2, ZIP3, ZIP4, ZIP5, ZIP6, ZIP7 (Catsup), ZIP8, ZIP9, ZIP10, ZIP11, ZIP12, ZIP13, ZIP14

The structure of a bacterial ZIP protein has been resolved.^[5]

References

1. Hara T, Takeda TA, Takagishi T, Fukue K, Kambe T, Fukada T (March 2017). "Physiological roles of zinc transporters: molecular and genetic importance in zinc homeostasis". The Journal of Physiological Sciences. 67 (2): 283–301. doi:10.1007/s12576-017-0521-4. PMC 10717645. PMID 28130681.
2. Thomas P, Converse A, Berg HA (February 2018). "ZIP9, a novel membrane androgen receptor and zinc transporter protein". General and Comparative Endocrinology. 257: 130–136. doi:10.1016/j.ygcen.2017.04.016. PMID 28479083.
3. Gati C, Stetsenko A, Slotboom DJ, Scheres SH, Guskov A (November 2017). "The structural basis of proton driven zinc transport by ZntB". Nature Communications. 8 (1): 1313. Bibcode:2017NatCo...8.1313G. doi:10.1038/s41467-017-01483-7. PMC 5670123. PMID 29101379.
4. Tan K, Sather A, Robertson JL, Moy S, Roux B, Joachimiak A (October 2009). "Structure and electrostatic property of cytoplasmic domain of ZntB transporter". Protein Science. 18 (10): 2043–52. doi:10.1002/pro.215. PMC 2786968. PMID 19653298.
5. Zhang T, Liu J, Fellner M, Zhang C, Sui D, Hu J (August 2017). "Crystal structures of a ZIP zinc transporter reveal a binuclear metal center in the transport pathway". Science Advances. 3 (8): e1700344. Bibcode:2017SciA....3E0344Z. doi:10.1126/sciadv.1700344. PMC 5573306. PMID 28875161.