Figure 6.
Putative mechanism for cofactor exchange between Lhx3 and Isl1. Only Ldb1LID is shown for simplicity. (A) Lhx3 and Ldb1 form a complex where Ldb1LID extends across both LIM domains of Lhx3. (B) Lhx3LIM2 binds more tightly than Lhx3LIM1 and for some of the time Lhx3LIM1 is exposed while Lhx3LIM2 remains bound. (C) Isl1LIM1 can bind the C-terminal half of Ldb1LID. (D) The C-terminal half of Isl1LBD is brought into close proximity to Lhx3 and binds Lhx3LIM1 (E, F) The N-terminal half of Ldb1LID dissociates from Lhx3LIM2 to bind Isl1LIM2, allowing the N-terminal half of Isl1LBD to bind Lhx3LIM2. Complexes in (C–F) are stabilised through the simultaneous binding to both Lhx3 and Isl1 recognition sites on target genes.