Interdomain Interactions of Radixin in Vitro(*)
- From the (1)Department of Biology, Center for Cancer Research and
- (2) Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- ** To whom correspondence should be addressed. Tel.: 617-253-3026; Fax: 617-253-6272; solomon{at}mit.edu.
Abstract
We have assayed the domains of the ERM protein radixin for binding activities in vitro. Affinity columns bearing the amino-terminal domain of radixin selectively bound a small subset of the proteins of the chicken
erythrocyte cytoskeleton. Two of those proteins were identified as radixin itself and band 4.1. In contrast, the carboxyl-terminal
domain of the molecule bound neither protein, and full-length radixin did not bind band 4.1 (binding of full-length radixin
to itself was not evaluated). Columns bearing a mixture of the amino- and carboxyl-terminal domains of radixin also failed
to bind radixin and band 4.1. These results suggested that the amino- and carboxyl-terminal sequences can interact with one
another either in cis or in trans, and so interfere with radixin's interactions with other ligands. Using affinity co-electrophoresis, we confirmed a direct
interaction in solution between the two radixin domains; the data are consistent with the formation of a 1:1 complex with
a dissociation constant of 
5 × 10
M. Competition between intramolecular and intermolecular interactions may help to explain the provocative and dynamic localization
of ERM proteins within cells.
Footnotes
-
↵§ Supported in part by a National Science Foundation predoctoral fellowship.
-
↵* This work was supported by National Institutes of Health Grants CA53395 (to F. S.) and NS26862 (to A. D. L.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
-
↵1 The abbreviations used are:
- NTA
-
nitrilotriacetic acid
- Pipes
-
1,4-piperazinediethanesulfonic acid
- FL
-
full-length radixin
- N-domain
-
amino-terminal domain
- C-domain
-
carboxyl-terminal domain.
-
↵2B. Winckler and F. Solomon, unpublished.
-
- Received July 17, 1995.
- Revision received August 15, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
