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. 2007 Oct 29;13(1):144–154. doi: 10.2478/s11658-007-0043-9

Syntaxin 8 has two functionally distinct di-leucine-based motifs

Kazuo Kasai 1,2,3, Kei Suga 1, Tetsuro Izumi 3, Kimio Akagawa 1,✉
PMCID: PMC6275627  PMID: 17965969

Abstract

Syntaxin 8 has been shown to form the SNARE complex with syntaxin 7, vti1b and endobrevin. These have been shown to function as the machinery for the homotypic fusion of late endosomes. Recently, we showed that syntaxins 7 and 8 cycle through the plasma membrane, and that the di-leucine-based motifs in the cytoplasmic domain of syntaxins 7 and 8 respectively function in their endocytic and exocytic processes. However, we could not elucidate the mechanism by which syntaxin 8 cycles through the plasma membrane. In this study, we constructed several different syntaxin 8 molecules by mutating putative di-leucine-based motifs, and analyzed their intracellular localization and trafficking. We found a di-leucine-based motif in the cytoplasmic domain of syntaxin 8. It is similar to that of syntaxin 7, and functions in its endocytosis. These results suggest that in the cytoplasmic domain, syntaxin 8 has two functionally distinct di-leucine-based motifs that act independently in its endocytic and exocytic processes. This is the first report on two di-leucine-based motifs in the same molecule acting independently in distinct transport pathways.

Key words: Syntaxin, Di-leucine-based motif, Endocytosis, Exocytosis

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Abbreviations used

HA

hemagglutinin

NSF

N-ethylmaleimide-sensitive factor

SNAP

soluble NSF-attachment protein

SNARE

SNAP-receptor

TGN

trans-Golgi network

t-SNARE

target-SNARE

v-SNARE

vesicle-SNARE

vti1b

Vps10p tail interactor 1b

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