Figure 7. Protein–protein interactions occur between OTX2 and MITF-A. A: Full-length (FL) MITF-A and OTX2 and their known domains are shown with the corresponding amino acids as follows: MITF-A specific N-terminal (A), N-terminal region common in MITF-A and several other isoforms (B1b), activation domain (AD), basic helix–loop–helix leucine zipper (bHLH-LZ), and serine-rich C-terminal activation domain (S); OTX2 DNA-binding homeodomain (HD); and N- and C-terminal activation domains (ND, CD). B: Interactions of full-length OTX2 with various MITF-A domains (FL: aa1–520; A-B1b-AD: aa1–297; A-B1b: aa1–124; B1b-AD: aa36–297; AD: aa118–297; bHLH-LZ: aa295–405 or S: aa402–520) are shown by gray columns. Auto-activation of each “bait” MITF-A domain alone is indicated by white columns and for the full-length OTX2 “prey” construct by the hatched column. C: Interactions of selected MITF-A domains (FL, A-B1b-AD, AD, or S) with various OTX2 domains (FL: aa1−297; ND: aa1−37; HD: aa37−109 or CD: aa107−297) were assessed (gray columns) and compared with empty “bait” vectors (white columns). Assays were controlled with the yeast strain carrying empty “bait” and “prey” vectors or the positive control mCAR/SRC1 (black columns). Results are means±SEM relative to the maximal activation of the β-galactosidase reporter (=100) from three independent assays each performed in quadruplicate..