title: Ribosomal protein S3 (rpS3) secreted from various cancer cells is N-linked glycosylated.
abstract: Ribosomal protein S3 (rpS3) is a 243 amino acid component of the 40S ribosomal small subunit. It has multiple roles in translation and extra-ribosomal functions like apoptosis and DNA repair. RpS3 is secreted only in cancer cell lines. Presently, mass spectrometry analysis revealed rpS3 to be glycosylated at the Asn165 residue. A point mutation at this residue decreased secretion of rpS3 in cancer cell lines. Secretion was also inhibited by the endoplasmic reticulum (ER)-Golgi transport inhibitor Brefeldin A and by Tunicamycin, an inhibitor of N-linked glycosylation. N-linked glycosylation of rpS3 was confirmed as necessary for rpS3 secretion into culture media via the ER-Golgi dependent pathway. RpS3 bound to Concanavalin A, a carbohydrate binding lectin protein, while treatment with peptide-N-glycosidase F shifted the secreted rpS3 to a lower molecular weight band. In addition, the N165G mutant of rpS3 displayed reduced secretion compared to the wild-type. An in vitro binding assay detected rpS3 homodimer formation via the N-terminal region (rpS3:1-85) and a middle region (rpS3:95-158). The results indicate that the Asn 165 residue of rpS3 is a critical site for N-linked glycosylation and passage through the ER-Golgi secretion pathway.
authors.affiliation: Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
authors.forename: YongJoong
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Min Seon
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Hag Dong
authors.initials: HD
authors.lastname: Kim
authors.affiliation: Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Joon
authors.initials: J
authors.lastname: Kim
mesh_terms: D000818:Animals; D001216:Asparagine; D020126:Brefeldin A / Q000494:pharmacology; D045744:Cell Line, Tumor; D002465:Cell Movement; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D051379:Mice; D008985:Monensin / Q000494:pharmacology; D041681:NIH 3T3 Cells; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017354:Point Mutation; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: C578290:RPS3 protein, human; D012269:Ribosomal Proteins; D014415:Tunicamycin; D020126:Brefeldin A; D001216:Asparagine; D008985:Monensin
keywords: glycosylation; ribosomal protein S3; ribosome; secretion