CHARACTERIZATION OF RECOMBINANT HUMAN INTERLEUKIN-4 RECEPTOR FROM CHOCELLS - ROLE OF N-LINKED OLIGOSACCHARIDES

Interleukin 4 (IL-4) mediates its biological activities through intera ction with its receptor on the cell surface. A recombinant extracellul ar domain of the alpha subunit of human interleukin 4 receptor was exp ressed in CHO cells and purified to homogeneity by a combination of io n exchange and immunoaffinity chromatography. Analysis of the purified protein by MALDI MS provided an average mass of 38,241 Da while micro sequencing identified the site of the signal sequence processing to be SeT23-G1Y(24) The receptor was highly glycosylated,containing N-linke d complex oligosaccharides with bi-, tri-, and tetraantennary structur es. Five of the six potential glycosylation sites could be assigned to Asn residues 53, 98, 128, 134 and 176. N-deglycosylation increased ag gregation and reduced solubility of the receptor but did not affect it s IL-4 binding activity. These observations provide preliminary insigh ts into the role of N-linked oligosaccharides in IL-4 receptor biosynt hesis and function at the cell surface. (C) 1995 Academic Press, Inc.