Interdomain interactions of radixin in vitro.
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 approximately 5 x 10(-8) M. Competition between intramolecular and intermolecular interactions may help to explain the provocative and dynamic localization of ERM proteins within cells.
Magendantz
M
M
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Henry
M D
MD
Lander
A
A
Solomon
F
F
D000818:Animals; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism*; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004912:Erythrocytes / Q000737:chemistry; D015151:Immunoblotting; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism
D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D008024:Ligands; D008565:Membrane Proteins; D009479:Neuropeptides; D010446:Peptide Fragments; D011994:Recombinant Proteins; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; C071776:radixin