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Figure 1.
Figure 1. Scaffolding in Drosophila Vision
(A)
Scaffolding in Drosophila vision. Photon absorption by rhodopsin
(1) sequentially activates Gqα (2), PLC-β (3), and TRP cation
channels (4). Calcium influx (5) activates an eye-specific
kinase (eye-PKC, 6) which phosphorylates the TRP channel (7) and
the INAD scaffold (in red, 8). Through its PDZ domains, INAD
assembles a core macromolecular complex involving PLC-β, TRP,
and eye-PKC.
(B) Structural overlay of three previously
characterized PDZ domains (PDB codes 1BE9, 1G9O, and 2F5Y).
(C) The atomic structure of PDZ5 shows overall similarity in the
β sheets, but significant conformational changes in both α
helices (see Figure S1 for quantitation). Examination of the
2F[o] − F[c] electron density at 1σ indicates the presence of
a disulfide bond between cysteines 606 and 645.
(D)
Sequence alignment of the PDZ domains shown. The color code
corresponds to the structures in (B) and (C); the positions of
the two cysteines are highlighted in the alignment.
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