Translocation of a fragment of invertase across microsomal vesicles isolated from Neurospora crassa requires the hydrolysis of a nucleoside triphosphate.
The step which requires the hydrolysis of a nucleoside triphosphate for translocation of a protein across microsome was investigated by studying translocation uncoupled from translation using two truncated products of invertase: one product contains the first 262 amino acids of the secreted invertase (Inv262); the other, the first 104 amino acids (Inv104). The truncated products were translated from RNA transcripts without a stop codon. It is demonstrated that the translated products contain an associated ribosome, and the associated ribosome is essential for the posttranslational translocation phenomenon. Also, it is demonstrated that binding of Inv262 to microsomal vesicles made from the cell wall-less mutant of Neurospora crassa does not require the hydrolysis, or the presence, of a nucleoside triphosphate. However, the posttranslational translocation across the membrane, as monitored by glycosylation of the translocated polypeptide chain, does. The data suggest that a nucleoside triphosphatase activity is associated with the translocation of invertase across the membrane. Furthermore, it is demonstrated that binding, and subsequent translocation across the membrane, is dependent on trypsin-sensitive membrane component(s).
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Laboratory of Cell Biology, Rockefeller University, New York, New York 10021-6399.
D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D006868:Hydrolysis; D007425:Intracellular Membranes / Q000201:enzymology*; D008861:Microsomes / Q000201:enzymology*; D008970:Molecular Weight; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*; D010446:Peptide Fragments / Q000378:metabolism*; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D012265:Ribonucleotides / Q000378:metabolism*; D014158:Transcription, Genetic; D043324:beta-Fructofuranosidase
D010446:Peptide Fragments; D012265:Ribonucleotides; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase