Syntaxin 3 is essential for photoreceptor outer segment protein trafficking and survival
Mashal Kakakhel, Lars Tebbe, Mustafa S. Makia, Shannon M. Conley, David M. Sherry, Muayyad R. Al-Ubaidi, Muna I. Naash
Abstract
Significance Rod and cone photoreceptors are highly polarized cells which rely on incompletely understood trafficking pathways to deliver and sort proteins into multiple outer segment subcompartments (disc, rim, and plasma membrane). Here we identify the SNARE protein syntaxin 3 as a trafficking component for both disc and rim proteins but not plasma membrane proteins. Our results suggest that syntaxin 3-mediated vesicle fusion is a convergence point for disc and rim protein trafficking and sorting. Furthermore, we find no evidence that eliminating syntaxin 3 affects cone photoreceptor trafficking, suggesting that divergent trafficking pathways in the two cell types may underlie their different outer segment structure. These studies significantly enhance our understanding of the unique and elegant cell biology of the photoreceptor.