title: The roles of Syx5 in Golgi morphology and Rhodopsin transport in Drosophila photoreceptors.
abstract: SNAREs (SNAP receptors) are the key components of protein complexes that drive membrane fusion. Here, we report the function of a SNARE, Syntaxin 5 (Syx5), in the development of photoreceptors in Drosophila In wild-type photoreceptors, Syx5 localizes to cis-Golgi, along with cis-Golgi markers: Rab1 and GM130. We observed that Syx5-deficient photoreceptors show notable accumulation of these cis-Golgi markers accompanying drastic accumulation of vesicles between endoplasmic reticulum (ER) and Golgi cisternae. Extensive analysis of Rh1 (rhodopsin 1) trafficking revealed that in Syx5-deficient photoreceptors, Rh1 is exported from the ER with normal kinetics, retained in the cis-Golgi region along with GM130 for a prolonged period, and then subsequently degraded presumably by endoplasmic reticulum-associated protein degradation (ERAD) after retrieval to the ER. Unlike our previous report of Rab6-deficient photoreceptors - where two apical transport pathways are specifically inhibited - vesicle transport pathways to all plasma membrane domains are inhibited in Syx5-deficient photoreceptors, implying that Rab6 and Syx5 are acting in different steps of intra-Golgi transport. These results indicate that Syx5 is crucial for membrane protein transport, presumably during ER-derived vesicle fusion to form cis-Golgi cisternae.
authors: Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan.
authors: Takunori
authors: T
authors: Satoh
authors: Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan.
authors: Yuri
authors: Y
authors: Nakamura
authors: Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan aksatoh@hiroshima-u.ac.jp.
authors: Akiko K
authors: http://orcid.org/0000-0001-7336-6642
authors: AK
authors: Satoh
keywords: ER; Golgi; Rhodopsin; Syx5; Vesicle cluster