Role of Aquaporin-6 in Rat Parotid Secretory Granules

Aquaporin-6 (AQP6) is a unique member of the family of AQP water channels and is involved in anion permeability. AQP6 was initially discovered in the cytoplasm of kidney cells as a kidney-specific AQP; however, subsequent studies revealed that the brain, inner ear, vestibular and intestines also express AQP6. Recently, we demonstrated that reactivity with an AQP6 antibody was observed in rat parotid granule membranes using immunohistochemistry. Those findings suggest that AQP6 participates as an anion channel in parotid secretory granule membranes. Here, we review the role of AQP6 in organelle membranes and introduce our challenge to elucidate the specific function of AQP6 in rat parotid granule osmoregulation.