Preferential association of syntaxin 8 with the early endosome.
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.
Subramaniam
V N
VN
Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Singapore 117609, Singapore.
Loh
E
E
Horstmann
H
H
Habermann
A
A
Xu
Y
Y
Coe
J
J
Griffiths
G
G
Hong
W
W
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002999:Clone Cells; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D008099:Liver / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D050765:Qa-SNARE Proteins; D051381:Rats; D016415:Sequence Alignment
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins