Binding of unglycosylated and glycosylated human recombinant interferon-gamma to cellular receptors.
Recombinant human interferons (IFNs), either unglycosylated produced in E. coli (rIFN-gamma) or glycosylated produced in CHO cells (g-rIFN-gamma), were labeled with 125I to similar specific activities to study their interaction with cell-surface receptors. When analyzed by gel electrophoresis, rIFN-gamma run as a single polypeptide of Mr 15,000-17,000, whereas g-rIFN-gamma separated into three components of Mr 20,000, 22,000, and 43,000, which corresponded to the known size of the two monomeric and one dimeric forms of glycosylated natural IFN-gamma. The binding of the two species of 125I-IFN-gamma was competed equally by rIFN-gamma in competition displacement experiments with Daudi cells, indicating that these IFNs bind with similar high affinity to the same receptors. KD values of 1.25 X 10(-10) and 2.5 X 10(-10) M were determined for g-rIFN-gamma and rIFN-gamma, respectively. This relatively small difference in KD does not apparently result in a detectable difference in biological activity, as measured by the increase in 2',5'-oligo(A) synthetase activity in IFN-treated HeLa and A549 cells. These results indicate that glycosylation of IFN-gamma does not play a significant role in its interaction with cellular receptors and in the induction of a biological response.
Littman
S J
SJ
Devos
R
R
Baglioni
C
C
D015088:2',5'-Oligoadenylate Synthetase / Q000378:metabolism; D002460:Cell Line; D004926:Escherichia coli / Q000235:genetics; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D011971:Receptors, Immunologic / Q000378:metabolism*; D017471:Receptors, Interferon; D011994:Recombinant Proteins / Q000378:metabolism*; D013329:Structure-Activity Relationship
D011971:Receptors, Immunologic; D017471:Receptors, Interferon; D011994:Recombinant Proteins; C046697:glycosylated gamma interferon; D007371:Interferon-gamma; D015088:2',5'-Oligoadenylate Synthetase