The anion exchanger and Na+K(+)-ATPase interact with distinct sites on ankyrin in in vitro assays.

Journal Article

This report demonstrates that the high affinity binding of ankyrin to two well characterized ankyrin-binding proteins, the erythrocyte anion exchanger and kidney Na+K(+)-ATPase, requires interaction of these proteins with unique sites on the ankyrin molecule. Binding of 125I-labeled erythrocyte ankyrin and ankyrin proteolytic domains was measured to the anion exchanger and Na+K(+)-ATPase incorporated into phosphatidylcholine liposomes. 125I-Labeled ankyrin associated with both anion exchanger and Na+K(+)-ATPase liposomes with a high affinity (KD ranging from 10 to 25 nM), and a capacity approaching 1 mol of ankyrin/2 mol of ATPase and 1 mol of ankyrin/8 mol of anion exchanger. The 43 kDa cytoplasmic domain of the erythrocyte anion exchanger inhibited binding of ankyrin to both the anion exchanger and Na+K(+)-ATPase liposomes with a 50% reduction at approximately 90 nM for both proteins. Further binding experiments using proteolytic domains derived from ankyrin demonstrated the following differences between the anion exchanger and Na+K(+)-ATPase in interactions with ankyrin: 1) 125I-Labeled Na+K(+)-ATPase associated with both the 89-kDa domain as well as the spectrin binding domain of ankyrin, while the anion exchanger only associated with the 89-kDa domain. 2) The 125I-labeled 89-kDa domain of ankyrin associated with Na+K(+)-ATPase liposomes with at least a 20-fold lower affinity compared with intact ankyrin while this domain associated with the anion exchanger with a 2-3-fold increase in affinity compared with intact ankyrin. 3) The 125I-labeled spectrin-binding domain of ankyrin associated with the Na+K(+)-ATPase liposomes to at least an 8-fold greater extent than to anion exchanger liposomes. The data are consistent with an independent acquisition of high affinity ankyrin binding activity for the anion exchanger and Na+K(+)-ATPase proteins through a convergent evolutionary process.

Full Text

Duke Authors

Cited Authors

  • Davis, JQ; Bennett, V

Published Date

  • October 5, 1990

Published In

Volume / Issue

  • 265 / 28

Start / End Page

  • 17252 - 17256

PubMed ID

  • 2170369

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States