Fig. 6

Fig. 6

The Extracellular Domain of Crb2a Is Required for Crb2a to Mediate Photoreceptor Adhesion (A) The schematics illustrate the two strategies to transgenically express Crb2a, Crb2a-Δ^EX-mCherry^out, Crb2a-Δ^EX-mCherryⁱⁿ, Crb2a-Δ^EX, Crb3a-mCherry^out, or Crb3a in zebrafish retina. Individual protein domains are labeled as follows: SP, the signal peptide; Ex., the extracellular domain; T, the transmembrane domain; In., the intracellular domain; mC, mCherry; GFP, green florescent protein; -Δ^EX, absence of the extracellular domain. The percentages of transgenic photoreceptors that formed rosettes in 5-dpf crb2a^m289 mutant retinas were quantified and summarized in the table. (B and C) Crb2a-Δ^EX-mCherry^out-expressing photoreceptors (red) scattered randomly in the crb2a^m289 mutant retinas. (C) shows magnified images of two transgenic cells that abutted each other but did not appear to adhere (the contours illustrates the lack of a flat-adhering junctional interface, arrow). (D and E) Transgenic photoreceptors that coexpressed Crb2a-Δ^EX and GFP also scattered randomly in the crb2a^m289 mutant retinas. (E) shows magnified images of three transgenic cells, two of which abutted but did not adhere to each other to establish a flat junctional interface (contours, arrow). The lack of Crb2a staining confirmed that the embryo was a crb2a^m289 mutant. See Figure S5 for effects of transgenic expressing Crb2a-Δ^EX-mCherryⁱⁿ, Crb3a-mCherry^out, and Crb3a in either wild-type or crb2a^m289 mutant embryos.