title: High-affinity potassium uptake system in Bacillus acidocaldarius showing immunological cross-reactivity with the Kdp system from Escherichia coli.
abstract: During growth with low levels of K+, Bacillus acidocaldarius expressed a high-affinity K+ uptake system. The following observations indicate that this system strongly resembles the Kdp-ATPase of Escherichia coli: (i) its high affinity for K+ (Km of 20 microM or below); (ii) its poor transport of Rb+; (iii) the enhanced ATPase activity of membranes derived from cells grown with low levels of K+ (this activity was stimulated by K+ and inhibited by vanadate); (iv) the expression of an extra protein with a molecular weight of 70,000 in cells grown with low levels of K+; and (v) the immunological cross-reactivity of this 70,000-molecular-weight protein with antibodies against the catalytic subunit B of the E. coli Kdp system. Antibodies against the complete E. coli Kdp system, which immunoprecipitated the whole E. coli KdpABC complex, almost exclusively precipitated the 70,000-molecular-weight protein from detergent-solubilized B. acidocaldarius membranes. The possibility that the B. acidocaldarius Kdp system consists of a single, KdpB-type subunit is discussed.
mesh_terms: D000251:Adenosine Triphosphatases / Q000276:immunology* / Q000378:metabolism; D000907:Antibodies, Bacterial / Q000276:immunology; D001407:Bacillus / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000276:immunology*; D001692:Biological Transport; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003429:Cross Reactions; D004926:Escherichia coli / Q000276:immunology / Q000378:metabolism*; D007118:Immunoassay; D007700:Kinetics; D011188:Potassium / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D000251:Adenosine Triphosphatases; D011188:Potassium