Preferential association of syntaxin 8 with the early endosome

Abstract

Members of the syntaxin family play a fundamental role in vesicle docking and fusion of diverse transport events. We have molecularly characterized syntaxin 8, a novel member of the syntaxin family. The nucleotide sequence of cloned rat cDNA predicts a polypeptide of 236 residues with a carboxyl-terminal 18-residue hydrophobic domain that may function as a membrane anchor. Characteristic of syntaxins, syntaxin 8 also contain regions that have the potential to form coiled-coil structures. Among the known syntaxins, syntaxin 8 is most homologous to syntaxin 6 which is predominantly associated with the trans-Golgi network (TGN). The syntaxin 8 transcript is detected in all rat tissues examined by northern blot. Antibodies against recombinant syntaxin 8 recognize a 27 kDa protein that is enriched in membrane fractions containing the Golgi apparatus and the endosomal/lysosomal compartments. Syntaxin 8 in membrane extract could be incorporated into a 20S protein complex in a way that is dependent on the soluble N-ethylmaleimide-sensitive factor (NSF) and soluble NSF attachment protein ((alpha)-SNAP), suggesting that syntaxin 8 is indeed a SNAP receptor (SNARE). Indirect immunofluorescence microscopy reveals that the majority of syntaxin 8 is localized to the early endosome marked by Rab5. This is corroborated by immunogold labeling experiments showing enrichment of syntaxin 8 in the early endosome and its co-labeling with Rab5.

A SNARE complex mediating fusion of late endosomes defines conserved properties of SNARE structure and function

“…However, this may be partly due to overexpression since the native protein is also detectable in endosomes (our unpublished observations). Moreover, in accordance with our data it has recently been reported that vti1b coprecipitates with syntaxin 8 (Subramaniam et al ., 2000) and that endobrevin coprecipitates with syntaxin 7 (Mullock et al ., 2000).…”

Identification and validation of the reference genes in the echiuran worm Urechis unicinctus based on transcriptome data

“…The syntaxin family belongs to the t-SNARE subfamily of the SNARE superfamily and is involved in vesicle trafficking [ 62 , 63 ]. STX12 is widely expressed and potentially participates in a common trafficking event that occurs in every cell [ 64 – 66 ], which explains why STX12 showed stable expression levels during early development. The most stable reference gene in different adult tissues was euchromatic histone-lysine N-methyltransferase 1 ( EHMT1 ) (Fig.…”