Figure 4

Corto interacts in vitro directly with ERK and indirectly with dMP1. (A): GST pull-down assays show direct interaction between Corto and ERK. Top: Schematic representation of Corto full-length and truncated forms (black box: chromodomain; grey boxes: COOH-terminal globular domains). Bottom: Coomassie staining of fusion proteins (shown by arrows) and autoradiography of the GST pull-down assays with in vitro translated ³⁵S-ERK. (B): Leucine test of two-hybrid experiment shows that the NH₂-terminal half of Corto (LexA-C1/324 corresponding to amino-acids 1-324) interacts with full length dMP1 (B42AD-dMP1). Negative controls: LexA and B42AD-dMP1; LexA-C1/324 and B42AD; positive controls: LexA53 and B42ADT. (C): GST pull-down assays using a GST-dMP1 fusion protein show that the Corto-dMP1 interaction is not direct. Top: Coomassie staining of fusion proteins (shown by arrows). Middle: autoradiography of the GST pull-down assays showing no specific interaction between GST-dMP1 beads and in vitro translated ³⁵S-Corto. Bottom: peptide pull-down assay using total embryonic protein extract and GST-dMP1 shows that Corto (revealed by anti-Corto antibodies) is specifically retained on GST-dMP1 beads (shown by an arrow).