title: Circularly permuted interleukin 4 retains proliferative and binding activity.
abstract: In human interleukin 4(IL-4), the carboxyl and amino termini of the 129 amino acid hormone are close to each other and this region is believed to be important for binding to the IL-4 receptor (IL-4r). We constructed plasmids encoding circularly permuted IL-4 mutants with the peptide Gly-Gly-Asn-Gly-Gly (GGNGG) joining the carboxyl to the amino terminus and with new amino and carboxyl termini elsewhere. Mutant IL-4(38-37) is composed of IL-4 residues 38-129 GGNGG and 1-37. Mutant IL-4(105-104) is composed of IL-4 residues 105-129, GGNGG and 1-104. IL-4(38-37) and IL-4(105-104) were purified from E. coli to near homogeneity and retained 50-100% of the binding and proliferative activity of IL-4, and in addition retained the ability to upregulate CD23 on Burkitt's lymphoma cells. Circular dichroism studies indicated that the tertiary structures of both IL-4(38-37) and IL-4(105-104) were retained, with the former molecule most similar to native IL-4. We conclude that while both native termini of IL-4 may be near its binding site, neither is required to be free for optimum activity.
authors.affiliation: Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Kreitman
authors.forename: R K
authors.initials: RK
authors.lastname: Puri
authors.forename: P
authors.initials: P
authors.lastname: McPhie
authors.forename: I
authors.initials: I
authors.lastname: Pastan
mesh_terms: D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D001483:Base Sequence; D002051:Burkitt Lymphoma / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002942:Circular Dichroism; D004926:Escherichia coli; D006801:Humans; D015847:Interleukin-4 / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D017455:Receptors, IgE / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D017455:Receptors, IgE; D011993:Recombinant Fusion Proteins; D015847:Interleukin-4