A 45-kDa protein antigenically related to band 3 is selectively expressed in kidney mitochondria.
Anion exchange similar to that catalyzed by erythrocyte band 3 occurs across many nonerythroid cell membranes. To identify anion-exchange proteins structurally related to band 3, we immunoblotted rabbit kidney medullary membrane fractions with anti-band 3 antibodies. Immunoblots using antibodies to the cytoplasmic domain of band 3 revealed cross-reactive proteins in the plasma membrane fraction only. In contrast, two monoclonal antibodies against band 3 membrane domain labeled a 45-kDa protein; further immunoblotting and immunogold studies of membrane fractions and kidney sections using one of the anti-membrane domain antibodies showed that labeling was strongest in mitochondria of H(+)-secreting collecting duct cells. Tissue-to-tissue expression of the 45-kDa mitochondrial protein was variable: kidney medulla greater than heart greater than kidney cortex much greater than liver. We conclude that a 45-kDa protein with immunological cross-reactivity to the erythrocyte band 3 membrane domain is expressed in mitochondria in a highly cell-specific fashion and speculate that the protein may play a role in mitochondrial anion transport.
Ostedgaard
L S
LS
Department of Medicine, University of Iowa, Iowa City 52242.
Jennings
M L
ML
Karniski
L P
LP
Schuster
V L
VL
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000276:immunology*; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000032:analysis; D002462:Cell Membrane / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis; D004910:Erythrocyte Membrane / Q000378:metabolism; D015151:Immunoblotting; D007668:Kidney / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology / Q000302:isolation & purification*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism*; D008970:Molecular Weight; D009928:Organ Specificity; D011817:Rabbits
D001457:Anion Exchange Protein 1, Erythrocyte; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000939:Epitopes; D008565:Membrane Proteins