Crag is a GEF for Rab11 required for rhodopsin trafficking and maintenance of adult photoreceptor cells.

• Main Authors: Bo Xiong, Vafa Bayat, Manish Jaiswal, Ke Zhang, Hector Sandoval, Wu-Lin Charng, Tongchao Li, Gabriela David, Lita Duraine, Yong-Qi Lin, G Gregory Neely, Shinya Yamamoto, Hugo J Bellen
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2012-01-01
• Series: PLoS Biology
• Online Access: https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23226104/?tool=EBI
• ISSN: 1544-9173; 1545-7885

Rhodopsins (Rhs) are light sensors, and Rh1 is the major Rh in the Drosophila photoreceptor rhabdomere membrane. Upon photoactivation, a fraction of Rh1 is internalized and degraded, but it remains unclear how the rhabdomeric Rh1 pool is replenished and what molecular players are involved. Here, we show that Crag, a DENN protein, is a guanine nucleotide exchange factor for Rab11 that is required for the homeostasis of Rh1 upon light exposure. The absence of Crag causes a light-induced accumulation of cytoplasmic Rh1, and loss of Crag or Rab11 leads to a similar photoreceptor degeneration in adult flies. Furthermore, the defects associated with loss of Crag can be partially rescued with a constitutive active form of Rab11. We propose that upon light stimulation, Crag is required for trafficking of Rh from the trans-Golgi network to rhabdomere membranes via a Rab11-dependent vesicular transport.