PT - JOURNAL ARTICLE AU - Satoh, Takunori AU - Inagaki, Tsuyoshi AU - Liu, Ziguang AU - Watanabe, Reika AU - Satoh, Akiko K. TI - GPI biosynthesis is essential for rhodopsin sorting at the <em>trans</em>-Golgi network in <em>Drosophila</em> photoreceptors AID - 10.1242/dev.083683 DP - 2013 Jan 15 TA - Development PG - 385--394 VI - 140 IP - 2 4099 - http://dev.biologists.org/content/140/2/385.short 4100 - http://dev.biologists.org/content/140/2/385.full SO - Development2013 Jan 15; 140 AB - Sorting of integral membrane proteins plays crucial roles in establishing and maintaining the polarized structures of epithelial cells and neurons. However, little is known about the sorting mechanisms of newly synthesized membrane proteins at the trans-Golgi network (TGN). To identify which genes are essential for these sorting mechanisms, we screened mutants in which the transport of Rhodopsin 1 (Rh1), an apical integral membrane protein in Drosophila photoreceptors, was affected. We found that deficiencies in glycosylphosphatidylinositol (GPI) synthesis and attachment processes cause loss of the apical transport of Rh1 from the TGN and mis-sorting to the endolysosomal system. Moreover, Na+K+-ATPase, a basolateral membrane protein, and Crumbs (Crb), a stalk membrane protein, were mistransported to the apical rhabdomeric microvilli in GPI-deficient photoreceptors. These results indicate that polarized sorting of integral membrane proteins at the TGN requires the synthesis and anchoring of GPI-anchored proteins. Little is known about the cellular biological consequences of GPI deficiency in animals in vivo. Our results provide new insights into the importance of GPI synthesis and aid the understanding of pathologies involving GPI deficiency.