PT  - JOURNAL ARTICLE
AU  - Satoh, Takunori
AU  - Nakamura, Yuri
AU  - Satoh, Akiko K.
TI  - The roles of Syx5 in Golgi morphology and Rhodopsin transport in <em>Drosophila</em> photoreceptors
AID  - 10.1242/bio.020958
DP  - 2016 Oct 15
TA  - Biology Open
PG  - 1420--1430
VI  - 5
IP  - 10
4099  - http://bio.biologists.org/content/5/10/1420.short
4100  - http://bio.biologists.org/content/5/10/1420.full
SO  - Biology Open2016 Oct 15; 5
AB  - 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.