aquaglyceroporin

Aquaglyceroporins are a subset of the aquaporin family of membrane channels that facilitate the passive transport of glycerol and other small uncharged solutes in addition to water. Like other aquaporins, they form tetrameric assemblies in biological membranes, and each monomer creates a pore through which solutes can diffuse. The substrate specificity is determined in part by the ar/R selectivity filter and conserved NPA motifs. Permeability can be modulated by pH, phosphorylation, and tissue-specific regulation.

In humans, classic aquaglyceroporins include AQP3, AQP7, AQP9, and the less clearly defined AQP10. AQP3 is expressed in skin and mucosa and transports water and glycerol; AQP7 in adipocytes enables glycerol efflux during lipolysis; AQP9 in liver facilitates glycerol uptake and metabolism; AQP10 has been reported in the small intestine as a glycerol transporter. Other organisms possess aquaglyceroporins as well; for example yeast Fps1 and plant PIP-type aquaporins act as glycerol channels that support osmoregulation and stress responses.

Aquaglyceroporins contribute to energy homeostasis, osmoregulation, and cellular glycerol balance, influencing lipid metabolism and stress responses. Their activity is regulated by hormonal signals, cellular pH, calcium levels, and phosphorylation-dependent trafficking in osmoregulatory tissues. Dysregulation or genetic variation in aquaglyceroporins can affect glycerol handling and may impact metabolic conditions such as obesity or diabetes, and they are being explored as potential therapeutic targets for edema reduction and cancer.