Distinct biochemical requirements for the budding, targeting, and fusion of ER-derived transport vesicles.
The transport of pro-alpha-factor from the ER to the Golgi apparatus in gently lysed yeast spheroplasts is mediated by diffusible vesicles. These transport vesicles contain core-glycosylated pro-alpha-factor and are physically separable from donor ER and target Golgi compartments. The formation of diffusible vesicles from the ER requires ATP, Sec12p, Sec23p, and GTP hydrolysis. The vesicles produced are functionally distinct from the ER: they transfer pro-alpha-factor to the Golgi apparatus faster and more efficiently than the ER, they do not require Sec12p or Sec23p to complete transfer, and transfer is resistant to GTP gamma S. Targeting of vesicles to the Golgi apparatus requires Ypt1p and Sec18p. Fusion of vesicles that have targeted requires calcium and ATP.
Rexach
M F
MF
Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
Schekman
R W
RW
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002118:Calcium / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D005656:Fungal Proteins / Q000378:metabolism / Q000493:pharmacokinetics; D006056:Golgi Apparatus / Q000378:metabolism / Q000502:physiology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D002479:Inclusion Bodies / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D009154:Mutation; D009711:Nucleotides / Q000378:metabolism / Q000502:physiology; D015388:Organelles / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
D005656:Fungal Proteins; D009711:Nucleotides; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D002118:Calcium