Transmembrane protein series one: Aquaporin

What are Aquaporins?

Aquaporin (AQPs) is a kind of membrane protein, which widely exists in prokaryotic and eukaryotic cell membranes and has the characteristics of highly selective transport of water molecules. In addition, AQP is also involved in various physiological and pathological processes of the body, including cell proliferation, apoptosis, migration, phagocytosis and nerve signal transduction.

The Discovery of Aquaporins

In 1985, Benga et al. first discovered the existence of water-permeating channel proteins in erythrocyte membrane. In 1988, Agre et al. discovered a transmembrane protein in the erythrocyte membrane while identifying the human Rh blood group antigen. The protein's molecular weight is 28 KD, so it named "channel-forming integral membrane protein (CHIP28)". Subsequently, Agre et al. identified the function of CHIP28 to transfer water and renamed it aquaporin1 (AQP1).

At present, A total of 13 AQP have been found in human bodies, which are AQP0-AQP12, belonging to the major intrinsic protein (MIP) family, composed of 250 ~ 295 amino acids.

Classification of Aquaporins

Aquaporins found in mammals can be divided into three subfamilies based on differences in gene structure and transport function.

The first subfamily is aquaporin, including AQP 0, AQP 1, AQP 2, AQP 4, AQP 5, AQP 6 and AQP 8. They are only permeable to water, except for AQP 6 and AQP 8. AQP 6 is permeable to anions, while AQP 8 is permeable to urea.

The second subfamily is aquaglyceroporin, including AQP 3, AQP 7, AQP 9 and AQP 10. The second subfamily can transport water and other small molecular solutes such as glycerin and urea.

The third subfamily is known as the superaquaporins, including AQP 11 and AQP 12.

Molecular Structure and Biochemical Properties of AQPs

The typical AQP gene structure contains a large exon (exon 1) encoding the amino terminus of AQP and three smaller exons (exons 2 ~ 4) encoding the hydroxy-terminus of AQP.

AQP1 is a glycoprotein. Its primary structure is a single peptide chain that spans the membrane 6 times. The amino and hydroxyl terminals are all located in the cell, and it contains 3 extracellular rings (A, C, E) and 2 intracellular rings (B, D). B ring and E ring are hydrophobic, and any variation will cause the decrease of the activity of aquaporin. The asparagine-valine-alanine (NPA) motifs located on the B and E rings are a common feature of members of the AQP family.

The tertiary structure of aquaporin is the "hourglass" model proposed by Jung et al. The hydrophobic B ring and E ring are located in and outside the cell respectively, and fold into the membrane lipid bilayer. The two NPAs are folded to form a single water channel, each of which is approximately a water molecule in size. The concentrated electrostatic field around the NPA prevents the passage of charged protons and other ions.

The structure of the AQP

Figure 1 The structure of the AQP

Distribution of Aquaporins

Aquaporin is widely distributed in various tissues and organs of the body, including nervous system, cardiovascular system, respiratory system, kidney, digestive system and reproductive system.

Nervous system: Aquaporin is widely expressed in central nervous system and peripheral nervous system. Aquaporin in the brain are mainly AQP1, AQP4 and AQP9.

Cardiovascular system: Human heart expressions include AQP1, AQP3, AQP4, AQP5, AQP7, AQP9, AQP10 and AQP11.

Respiratory system: Four aquaporins, AQP1, AQP3, AQP4 and AQP5, are mainly expressed in the respiratory system.

Kidney: The reabsorption of water by the kidneys is mainly mediated by AQP, which in turn completes the urine concentration process. The AQP types in the kidney are mainly AQP1-4, AQP6-8 and AQP11.

Digestive system: The main functions of the digestive system include digestion and absorption, both of which require liquid transport across the cell membrane. Aquaporins in the digestive system include AQP1, AQP3, AQP4, AQP8, and AQP9.

Reproductive system: Recent studies on the human reproductive system AQP have shown that aquaporins play an important physiological role in the reproductive system. AQP is associated with diseases of the reproductive system, such as polycystic ovary syndrome, ovarian tumors, etc.

In addition, aquaporins are also distributed in the skin system and musculoskeletal system.

The Function of the AQP

With the isolation and identification of a large number of aquaporins, aquaporins have been found to be not only water-selective channel proteins, but also many other physiological and biochemical functions, and are a class of multifunctional proteins. The new functions of different members are mainly related to the cells they are located in.

  • For example, AQP1 is mainly located on vascular endothelial cells and lymphatic vascular endothelial cells, which are mainly involved in the formation of blood vessels and lymphatic vessels.

  • AQP3 located on the surface of keratinocytes and dendritic cells of the skin is associated with skin moisturization, innate immunity, and acquired immunity; mutations in AQP3 localized on renal tubular epithelial cells are associated with the pathogenesis of polycystic kidney disease.

  • AQP4 is mainly located in glial cells and ependymal cells in the central nervous system, which is involved in the occurrence and maintenance of cerebral edema.

  • AQP5 locates on the surface of ovarian epithelial cells, which is related to the occurrence of ovarian epithelial tumors.

  • AQP8 and AQP9 were located in liver cancer cells, and their decreased expression was related to their anti-apoptotic properties.

AQP plays an important role in the pathogenesis of many diseases and can be used as a new target for pharmacological treatment.

CUSABIO provides the products you need for your research. At present, we can produce aquaporin-related proteins, antibodies and kit products.

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Aquaporin related proteins for your research

Target Product Name Code Expression System
AQP1 Recombinant Human Aquaporin-1(AQP1),partial CSB-EP001957HU E.coli
AQP1 Recombinant Human Aquaporin-1(AQP1),partial CSB-EP001957HUe0 E.coli
AQP4 Recombinant Human Aquaporin-4(AQP4),partial CSB-EP001964HU E.coli
AQP4 Recombinant Human Aquaporin-4(AQP4),partial CSB-YP001964HU Yeast
Aqp4 RecombinantMouseAquaporin-4(Aqp4),partial CSB-YP001964MO1 Yeast
Aqp4 Recombinant Mouse Aquaporin-4(Aqp4),partial CSB-YP001964MO1f3 Yeast
aqpZ Recombinant Escherichia coli Aquaporin Z(aqpZ),Nanodisc CSB-CF352724ENV-N in vitro E.coli expression system
AQPZ Recombinant Escherichia coli Aquaporin Z (aqpZ) (Active) CSB-CF352724ENV in vitro E.coli expression system
AQP1 Recombinant Human Aquaporin-1(AQP1) (Active) CSB-CF001957HU(A4) in vitro E.coli expression system

Aquaporin related antibodies for your research

Target Product Name Code Species Reactivity Tested Applications
AQP1 AQP1 Antibody CSB-PA009568 Human, Mouse, Rat WB, ELISA
AQP1 AQP1 Antibody CSB-PA001957GA01HU Human, Mouse, Rat ELISA, WB, IHC
AQP1 AQP1 Antibody CSB-PA076907 Human, Mouse, Rat ELISA, IHC
AQP1 AQP1 Antibody CSB-PA990867 Human, Mouse, Rat ELISA, WB, IHC
AQP1 AQP1 Antibody CSB-PA118586 Human ELISA, WB
AQP1 AQP1 Antibody CSB-PA16085A0Rb Human, Mouse, Rat ELISA, WB, IF, IP
AQP1 AQP1 Antibody CSB-PA16087A0Rb Human ELISA, IHC, IF
AQP10 AQP10 Antibody CSB-PA693604 Human ELISA, WB
AQP10 AQP10 Antibody CSB-PA853482LA01HU Human ELISA, IHC, IF
AQP11 AQP11 Antibody CSB-PA008895 Human, Mouse, Rat WB, ELISA
AQP11 AQP11 Antibody CSB-PA781210 Human ELISA, IHC
AQP12A/AQP12B AQP12A/AQP12B Antibody CSB-PA000912 Human WB, ELISA
AQP2 AQP2 Antibody CSB-PA000913 Human, Mouse, Rat, Monkey WB, IHC, IF, ELISA
AQP2 Phospho-AQP2 (S256) Antibody CSB-PA009580 Human, Mouse, Rat IHC, ELISA
AQP2 AQP2 Antibody CSB-PA597642 Human, Mouse, Rat ELISA, IHC
AQP2 AQP2 Antibody CSB-PA411017 Human, Mouse, Rat ELISA, IHC
AQP2 AQP2 Antibody CSB-PA16069A0Rb Human ELISA, IF
AQP3 AQP3 Antibody CSB-PA009603 Human, Mouse, Rat IHC, ELISA
AQP3 AQP3 Antibody CSB-PA203676 Human, Mouse, Rat ELISA, IHC
AQP3 AQP3 Antibody CSB-PA531552 Human, Mouse, Rat ELISA, WB, IHC
AQP3 AQP3 Antibody CSB-PA13909A0Rb Human ELISA, IHC, IF
AQP4 AQP4 Monoclonal Antibody CSB-MA000219 Human,Mouse,Rat ELISA,WB,IHC,IF
AQP4 AQP4 Monoclonal Antibody CSB-MA592955 Human,Mouse,Rat ELISA,WB,IHC,IF
AQP4 AQP4 Antibody CSB-PA000914 Human, Mouse, Rat WB, IHC, ELISA
AQP4 AQP4 Antibody CSB-PA001964GA01HU Human, Mouse, Rat ELISA, WB, IHC
AQP4 AQP4 Antibody CSB-PA579941 Human, Mouse, Rat ELISA, WB, IHC
AQP4 AQP4 Antibody CSB-PA905782 Human, Mouse, Rat ELISA, WB, IHC
AQP4 AQP4 Antibody CSB-PA11137A0Rb Human, Mouse ELISA, WB, IHC, IF
AQP4 AQP4 Antibody CSB-PA001964ESR1HU Human, Mouse ELISA, WB
AQP5 AQP5 Antibody CSB-PA000915 Human WB, IHC, ELISA
AQP5 AQP5 Antibody CSB-PA191314 Human ELISA, IHC
AQP5 AQP5 Antibody CSB-PA978373 Human ELISA, IHC
AQP8 AQP8 Antibody CSB-PA186529 Human ELISA, IHC
AQP8 AQP8 Antibody CSB-PA905788 Human ELISA, IHC

Aquaporin related ELISA kits for your research

Target Product Name Code Sample Type Sensitivity
AQP1 Human Aquaporin 1,AQP-1 ELISA Kit CSB-E08248h serum, plasma, cell culture supernates, cell lysates 3.9 pg/mL
AQP2 Rat Aquaporin 2,AQP-2 ELISA Kit CSB-E08243r serum, plasma, urine, tissue homogenates 1.56 ng/mL
AQP3 Human Aquaporin 3,AQP-3 ELISA Kit CSB-E08251h serum, plasma, tissue homogenates 0.078 ng/mL
AQP4 Human Aquaporin 4,AQP-4 ELISA Kit CSB-E08254h serum, plasma, tissue homogenates 0.039 ng/mL
AQP-4 Ab Human Aquaporin 4 Antibody,AQP-4 Ab ELISA Kit CSB-E13568h serum, plasma 0.39 ng/mL

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