Structural domains and sequence of FLNs and PC2, and their interaction identified by yeast two-hybrid assay.

<p>(<b>A</b>) Upper panel, domain structure of human filamins (FLNs), FLNA, FLNB and FLNC, and sequence alignment. FLNs share common features such as the N-terminal actin-binding domain (ABD) and a semi-rigid rod composed of 24 Ig-like repeats (∼96 aa each) interrupted by two short flexible hinges (H1 and H2). The PC2 binding domain is indicated. Lower panel, sequence alignment for FLNs C-terminus, which share 70–75% sequence similarity. (<b>B</b>) Structural domain of PC2 is shown, indicating both the intracellular N- and C- termini (PC2N and PC2C, FLN-interacting domains) and transmembrane spans (TMs). (<b>C</b>) Interaction data revealed by β-GAL induction assay in the yeast two-hybrid screen system. PC2N, PC2C, the C-terminus of polycystin-1 (PC1C) and the empty vector were used as bait. The C-termini of FLNs and the empty vector were used as prey. A bait-prey pair was co-transformed in the yeast strain Y187, and the β-GAL activity was determined based on the time when colonies turned blue in X-gal filter lift assays. “+++”, “++”, “+” and “–” indicate development of blue color within 1, 3 and 24 hours, and no development of blue color within 24 hours, respectively.