AQP4
GeneName
AQP4
Summary
AQP4, also known as aquaporin-4 or AQP-4, is a 35kDa integral membrane protein predominantly expressed in the brain, particularly in astrocytes, where it localises to the plasma membrane and astrocyte end-feet surrounding blood vessels. This protein functions as a water channel, facilitating the transport of water across cell membranes, thereby playing a crucial role in maintaining intracellular and extracellular water homeostasis. AQP4 is also involved in cerebrospinal fluid circulation and renal water homeostasis, and it forms homotetramers to achieve its functional activity.
Importance
AQP4 is relevant to: - Neurological disorders, such as aquaporin-4 antibody-positive neuromyelitis optica, due to its role in water transport and brain oedema. - Regulation of osmotic balance in the central nervous system, impacting conditions like cerebral ischaemia and traumatic brain injury. - Kidney function and fluid balance, influencing diseases related to renal water retention and dehydration. - Research into the mechanisms of neurodegeneration and neuroinflammation, as it mediates astrocytic responses to inflammatory signals.
Top Products
For researchers investigating AQP4, we recommend two primary antibodies that stand out for their performance and reliability. The first is the well-cited Anti-Aquaporin 4 antibody [4/18] (ab9512), a monoclonal antibody that has garnered 55 citations, highlighting its trustworthiness in the field. This antibody is particularly effective for immunohistochemistry (IHC), making it an excellent choice for tissue studies.In addition, we offer the recombinant Anti-Aquaporin 4 antibody [EPR24281-65] (ab259318), which has been validated in knockout models and is suitable for a broader range of applications, including IHC, western blotting (WB), immunocytochemistry (ICC), and flow cytometry (FC). With 13 citations, this recombinant antibody provides the batch-to-batch consistency that many researchers seek. Together, these antibodies provide robust options for studying AQP4 in various experimental contexts. The Human Aquaporin 4 ELISA Kit - Intracellular (ab290983) is an excellent option for researchers looking to measure AQP4 levels in their samples.
Abcam Product Citation Summary
The data indicates that AQP4 antibodies are being utilised in various applications, including immunohistochemistry and Western blotting, to study its role in different contexts such as blood-brain barrier permeability and cardiac tissue responses. The studies involve both mouse and rabbit models, highlighting the relevance of AQP4 in neurological and cardiac research.
Abcam Product Citation Table
Domain
Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA).
Function
Forms a water-specific channel (PubMed:19383790, PubMed:7559426, PubMed:8601457). Plays an important role in brain water homeostasis (PubMed:37143309). It is involved in glymphatic solute transport and is required for a normal rate of water exchange across the blood brain interface. Required for normal levels of cerebrospinal fluid influx into the brain cortex and parenchyma along paravascular spaces that surround penetrating arteries, and for normal drainage of interstitial fluid along paravenous drainage pathways. Thereby, it is required for normal clearance of solutes from the brain interstitial fluid, including soluble beta-amyloid peptides derived from APP. Plays a redundant role in urinary water homeostasis and urinary concentrating ability (By similarity).
Involvement in disease
Megalencephalic leukoencephalopathy with subcortical cysts 4, remitting
MLC4
An autosomal recessive disorder characterized by macrocephaly apparent in infancy, developmental delay, delayed walking, variable cognitive decline, behavioral abnormalities, and early-onset seizures. Brain imaging shows swelling of the cerebral white matter and subcortical cysts in the anterior temporal region. The severity of neurologic dysfunction and brain abnormalities tends to improve with time, indicating a remitting disease course.
None
The disease may be caused by variants affecting the gene represented in this entry.
Post-translational modifications
Phosphorylation by PKC at Ser-180 reduces conductance by 50%. Phosphorylation by PKG at Ser-111 in response to glutamate increases conductance by 40% (By similarity).
Isoform 2: Palmitoylated on its N-terminal region. Isoform 1: Not palmitoylated.
Sequence Similarities
Belongs to the MIP/aquaporin (TC 1.A.8) family.
Tissue Specificity
Detected in skeletal muscle (PubMed:29055082). Detected in stomach, along the glandular base region of the fundic gland (at protein level) (PubMed:8601457). Detected in brain, lung and skeletal muscle, and at much lower levels in heart and ovary (PubMed:7559426, PubMed:8601457).
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Basolateral cell membrane
- Multi-pass membrane protein
- Endosome membrane
- Cell membrane
- Sarcolemma
- Multi-pass membrane protein
- Cell projection
- Activation of the vasopressin receptor AVPR1A triggers AQP4 phosphorylation at Ser-180 and promotes its internalization from the cell membrane. Detected on brain astrocyte processes and astrocyte endfeet close to capillaries.
Alternative names
Aquaporin-4, AQP-4, Mercurial-insensitive water channel, WCH4, MIWC, AQP4