Aquaporin-11: a channel protein lacking apparent transport function expressed in brain.
BACKGROUND
The aquaporins are a family of integral membrane proteins composed of two subfamilies: the orthodox aquaporins, which transport only water, and the aquaglyceroporins, which transport glycerol, urea, or other small solutes. Two recently described aquaporins, numbers 11 and 12, appear to be more distantly related to the other mammalian aquaporins and aquaglyceroporins.


RESULTS
We report on the characterization of Aquaporin-11 (AQP11). AQP11 RNA and protein is found in multiple rat tissues, including kidney, liver, testes and brain. AQP11 has a unique distribution in brain, appearing in Purkinje cell dendrites, hippocampal neurons of CA1 and CA2, and cerebral cortical neurons. Immunofluorescent staining of Purkinje cells indicates that AQP11 is intracellular. Unlike other aquaporins, Xenopus oocytes expressing AQP11 in the plasma membrane failed to transport water, glycerol, urea, or ions.


CONCLUSIONS
AQP11 is functionally distinct from other proteins of the aquaporin superfamily and could represent a new aquaporin subfamily. Further studies are necessary to elucidate the role of AQP11 in the brain.
Gorelick
Daniel A
DA
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, USA. gorelick@ciwemb.edu
Praetorius
Jeppe
J
Tsunenari
Takashi
T
Nielsen
Søren
S
Agre
Peter
P
D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D001692:Biological Transport; D001923:Brain Chemistry; D016466:CHO Cells; D002460:Cell Line; D002540:Cerebral Cortex / Q000737:chemistry / Q000166:cytology; D006224:Cricetinae; D003412:Cricetulus; D004285:Dogs; D005260:Female; D006624:Hippocampus / Q000737:chemistry / Q000166:cytology; D006801:Humans; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000302:isolation & purification* / Q000502:physiology; D009474:Neurons / Q000737:chemistry; D009865:Oocytes; D009928:Organ Specificity; D011689:Purkinje Cells / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013737:Testis / Q000737:chemistry; D014982:Xenopus laevis
C511251:AQP11 protein, human; C503878:Aqp11 protein, mouse; D020346:Aquaporins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C511252:aquaporin 11, rat