Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 protein.
Water rapidly crosses the plasma membrane of red blood cells (RBCs) and renal tubules through specialized channels. Although selective for water, the molecular structure of these channels is unknown. The CHIP28 protein is an abundant integral membrane protein in mammalian RBCs and renal proximal tubules and belongs to a family of membrane proteins with unknown functions. Oocytes from Xenopus laevis microinjected with in vitro-transcribed CHIP28 RNA exhibited increased osmotic water permeability; this was reversibly inhibited by mercuric chloride, a known inhibitor of water channels. Therefore it is likely that CHIP28 is a functional unit of membrane water channels.
Preston
G M
GM
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Carroll
T P
TP
Guggino
W B
WB
Agre
P
P
D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins; D002463:Cell Membrane Permeability; D004553:Electric Conductivity; D004910:Erythrocyte Membrane / Q000378:metabolism*; D015151:Immunoblotting; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008627:Mercuric Chloride / Q000494:pharmacology; D015394:Molecular Structure; D009865:Oocytes / Q000378:metabolism*; D009994:Osmolar Concentration; D012313:RNA / Q000235:genetics; D013816:Thermodynamics; D014162:Transfection; D014867:Water / Q000378:metabolism*; D014982:Xenopus laevis
D020346:Aquaporins; D008565:Membrane Proteins; D014867:Water; D051398:Aquaporin 1; D008627:Mercuric Chloride; D012313:RNA