TY - JOUR
T1 - Synaptotagmin II expression partially rescues the growth defect of the yeast secl5 secretory mutant
AU - Damer, Cynthia K.
AU - Creutz, Carl E.
N1 - Funding Information:
We thank Mary Miller for assistance with the dilution plating assay. This study was supported by research grants from the NIH (NS31618 and GM53266).
PY - 1996
Y1 - 1996
N2 - Synaptotagmins are a family of calcium- and phospholipid-binding proteins implicated in the function of cell exocytosis. Synaptotagmins I and II are neurally expressed proteins thought to be involved in neurotransmitter release from neurons. We have expressed rat synaptotagmin II in several Saccharomyces cerevisiae temperature-sensitive secretory mutants that are defective in Golgi to plasma membrane vesicular transport. Synaptotagmin II expression was able to partially rescue the growth defect in one particular mutant, sec15. No suppression was observed when synaptotagmin II was expressed in sec1, sec2, sec4, sec5, sec6, sec8, sec9, sec14, sec17, or sec18. Two synaptotagmin II deletion mutants were also expressed in sec15 and screened for suppression. The expression of the cytoplasmic domain of synaptotagmin alone was not able to suppress the sec15 growth defect. In addition, the expression of a synaptotagmin II fragment lacking the second half of the cytoplasmic domain including the second C2 domain did not suppress sec15. We have isolated a membrane fraction enriched in post-Golgi vesicles from a sec15 strain expressing synaptotagmin II and found that synaptotagmin II co-purifies with this fraction, suggesting that the rat synaptotagmin II is targeted to membranes in yeast. Sec15p forms a large multisubunit protein complex that includes Sec6p and Sec8p. This protein complex is thought to function in a late stage of exocytosis in yeast. Sec6p and Sec8p homologs have been identified in mammalian cells. Our studies suggest that synaptotagmin may be a part of this complex or regulate its function in mammalian cells.
AB - Synaptotagmins are a family of calcium- and phospholipid-binding proteins implicated in the function of cell exocytosis. Synaptotagmins I and II are neurally expressed proteins thought to be involved in neurotransmitter release from neurons. We have expressed rat synaptotagmin II in several Saccharomyces cerevisiae temperature-sensitive secretory mutants that are defective in Golgi to plasma membrane vesicular transport. Synaptotagmin II expression was able to partially rescue the growth defect in one particular mutant, sec15. No suppression was observed when synaptotagmin II was expressed in sec1, sec2, sec4, sec5, sec6, sec8, sec9, sec14, sec17, or sec18. Two synaptotagmin II deletion mutants were also expressed in sec15 and screened for suppression. The expression of the cytoplasmic domain of synaptotagmin alone was not able to suppress the sec15 growth defect. In addition, the expression of a synaptotagmin II fragment lacking the second half of the cytoplasmic domain including the second C2 domain did not suppress sec15. We have isolated a membrane fraction enriched in post-Golgi vesicles from a sec15 strain expressing synaptotagmin II and found that synaptotagmin II co-purifies with this fraction, suggesting that the rat synaptotagmin II is targeted to membranes in yeast. Sec15p forms a large multisubunit protein complex that includes Sec6p and Sec8p. This protein complex is thought to function in a late stage of exocytosis in yeast. Sec6p and Sec8p homologs have been identified in mammalian cells. Our studies suggest that synaptotagmin may be a part of this complex or regulate its function in mammalian cells.
KW - C2 domain
KW - Neurotransmitter release
KW - SEC6
KW - SEC8
KW - Saccharomyces cerevisiae
UR - http://www.scopus.com/inward/record.url?scp=0030909250&partnerID=8YFLogxK
U2 - 10.1016/S0248-4900(97)86831-1
DO - 10.1016/S0248-4900(97)86831-1
M3 - Article
C2 - 9175268
AN - SCOPUS:0030909250
VL - 88
SP - 55
EP - 63
JO - Biology of the Cell
JF - Biology of the Cell
SN - 0248-4900
IS - 1-2
ER -