Aquaporin-7
Developmental stage
Expressed at late stages of spermatogenesis, from late to maturing spermatids (at protein level).
Domain
Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro/Ala-Ala/Ser (NPA).
Function
Aquaglyceroporins form homotetrameric transmembrane channels, with each monomer independently mediating glycerol and water transport across the plasma membrane along their osmotic gradient. Could also be permeable to urea (PubMed:9252401). Mediates the efflux of glycerol, formed upon triglyceride hydrolysis, to avoid its accumulation in adipocytes and to make it available to other tissues. In the kidney, mediates the reabsorption of glycerol, preventing its loss in urine, again participating to energy homeostasis. In pancreatic beta cells, it also mediates the efflux of glycerol, regulating its intracellular levels (By similarity).
Post-translational modifications
Phosphorylation by PKA could prevent the interaction with PLIN1.
Sequence Similarities
Belongs to the MIP/aquaporin (TC 1.A.8) family.
Tissue Specificity
Detected in heart, kidney and testis.
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Cytoplasmic vesicle membrane
- Multi-pass membrane protein
- Lipid droplet
- Internalized from the cell membrane in response to catecholamine-induced activation of PKA; detected on intracellular membranes and colocalizes with lipid droplets (By similarity). Colocalizes with PLIN1 in adipocytes, probably on lipid droplets (By similarity).
Alternative names
Aquaporin-7, AQP-7, Aquaglyceroporin-7, Aqp7