Co-translational processing and intracellular transport of rat salivary mucus glycoprotein

A. Slomiany, K. Mizuta, G. Zalesna, H. Tsukada, B. L. Slomiany

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

A preparation of peptidyl-tRNA from intact microsomes of mucin-synthesizing polysomes of sublingual salivary gland cells contained fatty-acylated galactosamine-free and galactosamine-enriched peptidyl-tRNA fractions, whereas trypsin-chymotrypsin treated microsomes yielded predominantly the acylated galactosamine-enriched peptidyl-tRNA complexes. Radioscanning and chemical analyses revealed that palmitate was substituted on all nascent peptides, except those shorter than 20 amino-acid residues. In contrast, the [35S]-methionine label was detected only on galactosamine-free peptides containing up to 70 amino acids. On SDS-polyacrylamide gel, the peptides released from galactosamineenriched tRNA complexes separated into a multitude of bands ranging in size from 6000 to 60,000 dalton, whereas the total preparation afforded peptides ranging from 2000 to 60,000 dalton. Pulse-chase experiments, using radiolabelled methionine, palmitic acid and N-acetylgalactosamine, combined with chemical characterization of the radiolabelled fatty acids and carbohydrates from purified peptidyl-tRNA, confirmed that the N-terminal fatty acylation and the initial O-glycosylation with N-acetylgalactosamine are the co-translational processes taking place as soon as peptide is sufficiently large to be acylated, trimmed, and translocated to the luminal site of endoplasmic membrane.

Original languageEnglish (US)
Pages (from-to)807-818
Number of pages12
JournalArchives of Oral Biology
Volume33
Issue number11
DOIs
StatePublished - 1988

All Science Journal Classification (ASJC) codes

  • Otorhinolaryngology
  • Dentistry(all)
  • Cell Biology

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