Multiple glycosylated forms of T cell-derived interleukin 3 (IL-3). Heterogeneity of IL-3 from physiological and nonphysiological sources.
Interleukin 3 (IL-3) derived from mouse T cells was biosynthetically labeled with either [35S]methionine or [3H]mannose, affinity-purified using various anti-IL-3 antibodies, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography revealed the same three major bands with Mr values of 21,500-22,500, 27,000-31,000, and 32,000-36,000, irrespective of whether the anti-IL-3 antibody had been directed to the N or C termini of the IL-3 polypeptide. Bioassay of eluates from the gels confirmed that all three bands exhibited IL-3 bioactivity. IL-3 produced from two nonphysiological sources, the myelomonocytic leukemia WEHI-3B or Cos 7 cells that had been transfected with an IL-3 cDNA clone, had in each case a different pattern of microheterogeneity. Treatment with either tunicamycin or N-glycanase resulted in IL-3 running as one band with Mr 16,000, corresponding to its 140-amino acid polypeptide chain. No evidence for proteolytic processing was detected. These results show that the Mr heterogeneity of IL-3 was highly dependent on the cellular source and is due to N-linked glycosylation.
Ziltener
H J
HJ
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Fazekas de St Groth
B
B
Leslie
K B
KB
Schrader
J W
JW
D000818:Animals; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D007377:Interleukin-3 / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D008358:Mannose / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
D007377:Interleukin-3; D014415:Tunicamycin; D008715:Methionine; D008358:Mannose