Aquaporin 12 (AQP12)

Human AQP12A encodes a deduced 295-amino acid protein with a calculated molecular mass of about 31 kD. The mouse and human AQP12A proteins share 72% sequence homology. Whereas typical members of the AQP family have 2 asparagine-proline-alanine (NPA) motifs, the human and mouse AQP12A proteins have 1 NPA motif and a variant asparagine-proline-threonine (NPT) motif. RNA dot blot analysis of multiple mouse tissues revealed expression only in the pancreas. In situ hybridization of mouse pancreas sections showed expression in the acinar cells, but not in the duct or islet cells. When expressed in Xenopus oocytes, AQP12A was retained in the cytoplasm and was not targeted to the plasma membrane. Transient transfection of EGFP-tagged AQP12A in HEK293 and COS-7 cells showed an intracellular granular staining pattern.