Lactoperoxidase-catalyzed iodination of sodium and potassium ion-activated adenosine triphosphatase in the Madin-Darby canine kidney epithelial cell line and canine renal membranes.
Experiments are described in which the large chain of (Na+ + K+)-ATPase is labeled by lactoperoxidase-catalyzed iodination either at its extracytoplasmic surface exclusively or at both its extracytoplasmic and its cytoplasmic surfaces simultaneously. The former was accomplished by labeling intact cells of the Madin-Darby canine kidney line, and the latter by labeling open membrane vesicles, also from canine kidney. A comparison of the specific radioactivities for the large chain from the open membranes and the large chain from the Madin-Darby canine kidney cells reveals that the former was labeled approximately 5-fold more extensively. This indicates that the large chain of (Na+ + K+)-ATPase is situated in the membrane such that more of its mass protrudes into the cytoplasm than into the extracytoplasmic environment.
D000818:Animals; D002460:Cell Line; D002850:Chromatography, Gel; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D004848:Epithelium / Q000201:enzymology; D007455:Iodine / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D007784:Lactoperoxidase / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D007455:Iodine; D007784:Lactoperoxidase; D010544:Peroxidases; D000254:Sodium-Potassium-Exchanging ATPase