Secretion in yeast: translocation and glycosylation of prepro-alpha-factor in vitro can occur via an ATP-dependent post-translational mechanism.
In an in vitro system comprising a yeast cell-free translation system, yeast microsomes and mRNA encoding prepro-alpha-factor, the translocation of this protein across the membrane of the microsomal vesicle and its glycosylation could b uncoupled from its translation. Such post-translational processing is dependent upon the presence of ATP in the system. It is not, however, affected by a variety of uncouplers, ionophores or inhibitors, including carbonyl cyanide m-chlorophenyl hydrazone (CCCP), valinomycin, nigericin, dinitrophenol (DNP), potassium cyanide (KCN) or N-ethyl maleimide (NEM). This mechanism of translocation is significant as it indicates that a protein of 18 000 daltons is capable of crossing an endoplasmic reticulum-derived membrane post-translationally. For the moment, this phenomenon seems to be restricted to prepro-alpha-factor in the yeast in vitro system. Neither invertase nor IgG chi light chain could be translocated post-translationally in yeast, nor was such processing observed for prepro-alpha-factor in a wheat germ system supplemented with canine pancreatic microsomes.
Rothblatt
J A
JA
Cell Biology Program, European Molecular Biology Laboratory, 6900 Heidelberg, FRG.
Meyer
D I
DI
D000255:Adenosine Triphosphate / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D000072235:Mating Factor; D010455:Peptides / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D010455:Peptides; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D000255:Adenosine Triphosphate