A t-SNARE of the endocytic pathway must be activated for fusion.
The t-SNARE in a late Golgi compartment (Tlg2p) syntaxin is required for endocytosis and localization of cycling proteins to the late Golgi compartment in yeast. We show here that Tlg2p assembles with two light chains, Tlg1p and Vti1p, to form a functional t-SNARE that mediates fusion, specifically with the v-SNAREs Snc1p and Snc2p. In vitro, this t-SNARE is inert, locked in a nonfunctional state, unless it is activated for fusion. Activation can be mediated by a peptide derived from the v-SNARE, which likely bypasses additional regulatory proteins in the cell. Locking t-SNAREs creates the potential for spatial and temporal regulation of fusion by signaling processes that unleash their fusion capacity.
Paumet
F
F
Cellular Biochemistry and Biophysics Program, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA.
Brügger
B
B
Parlati
F
F
McNew
J A
JA
Söllner
T H
TH
Rothman
J E
JE
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D021381:Protein Transport / Q000502:physiology; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; C083242:SNC2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C112252:TLG2 protein, S cerevisiae; C106736:VTI1 protein, S cerevisiae; D033921:Vesicular Transport Proteins