title: Cytochalasin B-binding proteins in rabbit erythrocyte membranes and their post-natal change in relation to the glucose carrier activity.
abstract: Two distinct, carrier-mediated glucose uptake processes, a fast, cytochalasin B-sensitive and a slow, cytochalasin B-insensitive flux are identified in parallel in newborn rabbit erythrocytes. The fast, cytochalasin B-sensitive carrier function disappears as rabbits age, and only the slow cytochalasin B-insensitive carrier function is observed with adult rabbit erythrocytes. Three different cytochalasin B binding sites are distinguished in newborn rabbit erythrocytes; a glucose-sensitive site (site I), a cytochalasin E-sensitive site (site II), and a site insensitive to both glucose and cytochalasin E. With adult rabbit erythrocytes, only a cytochalasin E-sensitive site is detected. With glucose-sensitive site disappears as rabbits age, with a time course which is comparable to that of the disappearance of the cytochalasin B-sensitive glucose carrier function. The cytochalasin E-sensitive cytochalasin B binding site does not increase during this change, thus the disappearance of the glucose-sensitive site is not due to its conversion to a cytochalasin E-sensitive site. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of rabbit erythrocyte ghosts revealed a partial decrease in each of the membrane polypeptides of approximate molecular weights of 240 000, 160 000 and 50 000 as rabbits aged. It is concluded that the cytochalasin B-sensitive glucose carrier of fetal rabbit erythrocytes, like that of the human erythrocyte, is tightly associated with the site I cytochalasin B-binding protein, while the cytochalasin B-insensitive glucose carrier, operative in adult rabbit erythrocytes, is not.
mesh_terms: D000375:Aging; D000818:Animals; D001693:Biological Transport, Active; D001786:Blood Glucose / Q000378:metabolism*; D003571:Cytochalasin B / Q000097:blood*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000097:blood*; D008970:Molecular Weight; D011817:Rabbits; D011955:Receptors, Drug / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D008565:Membrane Proteins; D011955:Receptors, Drug; D003571:Cytochalasin B