Cotranslational attachment of fatty acids to nascent peptides in gastric mucus glycoprotein.
Using gastric mucous cells which are involved exclusively in the synthesis of secretory O-glycosidic glycoprotein (mucin), the relationship between protein core synthesis and its acylation with fatty acids was investigated. Labeling of the cells with [3H]palmitic acid and [35S]methionine followed by isolation of peptidyl-tRNA and release of nascent peptides, indicated that these peptides contain covalently bound fatty acids. The high performance thin layer chromatography, SDS-gel electrophoresis, and radioactivity scanning revealed that the preparation contained three fractions labeled with palmitate (Mr 15,000-3,600) and two (Mr 1,500 and less) without this label. Based on these data and the nascent peptides amino acid analysis, we conclude that the protein core of the O-glycosidic glycoprotein is acylated with fatty acids during translation, when the peptide chain is longer than 21 amino acid residues.
D000818:Animals; D002474:Cell-Free System; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D009077:Mucins / Q000378:metabolism*; D010168:Palmitates / Q000378:metabolism*; D010169:Palmitic Acids / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D051381:Rats
D009077:Mucins; D010168:Palmitates; D010169:Palmitic Acids; D012346:RNA, Transfer, Amino Acyl; C019037:tRNA, peptidyl-