Protein 4.1R self-association: identification of the binding domain

Carmen M Pérez-Ferreiro , Eva Lospitao , Isabel Correas , Carmen M Pérez-Ferreiro (1)

1 Molecular Biology

Erythroid protein 4.1 (4.1R) stabilizes the spectrin-actin network and anchors it to the plasma membrane. To contribute to the characterization of non-erythroid protein 4.1R, we used sedimentation, pull-down, and coimmunoprecipitation assays to investigate the ability of protein 4.1R to establish inter/intramolecular associations. We demonstrated that the small 4.1R isoforms of 60 kDa (4.1R 60}), but not the larger isoforms of 80 and 135 kDa (4.1R 80} and 4.1R 135}), were self-associated, and that a domain contained in all 4.1R isoforms, the core region, was responsible for 4.1R self-association. Results from denaturing-renaturing experiments, in which an initially non-self-associated 4.1R 80} isoform became self-associated, suggested that an initially hidden core region was subsequently exposed. This hypothesis was supported by results from pull-down assays, which showed that the core region interacted with the amino-terminal end of the FERM (Four-point-one, Ezrin, Radixin, Moesin) domain that is present in 4.1R 80} and 4.1R 135} isoforms but absent from 4.1R 60} isoforms. Consistently, 4.1R 80} isoforms bound neither to each other nor to 4.1R 60} isoforms. We propose that 4.1R 60} isoforms are constitutively self-associated, whereas 4.1R 80} and 4.1R 135} self-association is prevented by intramolecular interactions.

Mots clés: Life Sciences

Carmen M Pérez-Ferreiro, Eva Lospitao, Isabel Correas, Carmen M Pérez-Ferreiro. Protein 4.1R self-association: identification of the binding domain. Biochemical Journal, 2006, 400 (3), pp.457-465. ⟨10.1042/BJ20060644⟩. ⟨hal-00478585⟩