Biomaterial Database

cDNA cloning of a functional water channel from toad urinary bladder epithelium. 1996

T Ma, and B Yang, and A S Verkman

Department of Medicine, University of California, San Francisco 94143-0521, USA.

A cDNA was cloned from the epithelium of toad (Bufo marinas) urinary bladder, based on homology to the mammalian aquaporins (AQP). The cDNA [947 base pairs (bp), identified as AQP-t1] encoded a 272-amino acid protein with 76% identity to mammalian aquaporin-1 (AQP-1) and 88% identity to frog water channel FA-CHIP. AQP-t1 cDNA was nearly identical to a fragment of a nonfunctional cDNA cloned recently from toad bladder ["AQP-TB"; J. Siner, A. Paredes, C. Hosselet, T. Hammond, K. Strange, and H.W. Harris, Am. J. Physiol. 270 (Cell Physiol. 39): C372-C381, 1996], except for reading frame shifts at bp 253, 264, and 682, two single amino acid deletions, a different 3'-coding sequence downstream from bp 786, and a different 5' sequence upstream from bp 9. Water permeability (Pf) in Xenopus laevis oocytes expressing AQP-t1 cRNA was strongly increased from (0.83 +/- 0.06) x 10(-3) cm/s (water-injected control) to (17 +/- 4) x 10(-3) cm/s, with 80% inhibition by 0.3 mM HgCl2; glycerol and urea permeabilities were not increased. Northern blot analysis showed a single AQP-t1 mRNA of 2.8 kb in eye > lung > urinary bladder > skin > stomach approximately heart, brain, and intestine. AQP-t1 mRNA expression was not changed by a 3-day dehydration of toads or an 8-h stimulation of Pf in isolated bladders by forskolin. These results indicate that the epithelium of toad urinary bladder expresses a functional homologue of AQP-1 and FA-CHIP that is probably not vasopressin regulated.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D008322	Mammals	Warm-blooded vertebrate animals belonging to the class Mammalia, including all that possess hair and suckle their young.	Mammalia,Mammal
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D009928	Organ Specificity	Characteristic restricted to a particular organ of the body, such as a cell type, metabolic response or expression of a particular protein or antigen.	Tissue Specificity,Organ Specificities,Specificities, Organ,Specificities, Tissue,Specificity, Organ,Specificity, Tissue,Tissue Specificities
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D001743	Urinary Bladder	A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.	Bladder,Bladder Detrusor Muscle,Detrusor Urinae,Bladder Detrusor Muscles,Bladder, Urinary,Detrusor Muscle, Bladder,Detrusor Muscles, Bladder
D002024	Bufo marinus	A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.	Rhinella marina,Toad, Giant,Toad, Marine,Giant Toad,Giant Toads,Marine Toad,Marine Toads,Toads, Giant,Toads, Marine
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D004848	Epithelium	The layers of EPITHELIAL CELLS which cover the inner and outer surfaces of the cutaneous, mucus, and serous tissues and glands of the body.	Mesothelium,Epithelial Tissue,Mesothelial Tissue,Epithelial Tissues,Mesothelial Tissues,Tissue, Epithelial,Tissue, Mesothelial,Tissues, Epithelial,Tissues, Mesothelial