The IL-13 receptor structure differs on various cell types and may share more than one component with IL-4 receptor.
We have reported on the expression and characteristics of IL-13R and have demonstrated that IL-13 competes for IL-4 binding while IL-4 did not compete for the IL-13 binding on some cell types. Based on these observations, and the size of IL-13 and IL-4 cross-linked proteins, we concluded that the receptor for IL-13 is complex and shares a subunit with the receptor for IL-4. To explore the complexity of the IL-13R, a wide variety of cell types was examined for IL-13 and IL-4 binding. We report in this work that IL-4 does not always bind well to cells that bind IL-13, but the reverse is also true. We also found that IL-4 can compete more effectively for IL-13 binding than IL-13 itself. Cross-linking studies support these observations and demonstrate that 125I-labeled IL-13 bound exclusively to a single 65- to 70-kDa protein in MA-RCC and U251 cells, while in TF-1 cells it cross-linked to two membrane proteins of 65 to 70 kDa and 140 kDa. Furthermore, by using a chimeric protein composed of IL-13 and Pseudomonas exotoxin A, we observed that IL-4 neutralized the cytotoxicity of the IL-13 toxin on COS-7 cells by blocking a common form of the two cytokine receptors. We propose that the 65- to 70-kDa form of the IL-13R is the predominant common component shared between IL-13 and IL-4R. However, the primary IL-4 binding (p140) protein also participates in the formation of the IL-13R complex in some cell types. In addition, the gamma(c) or another interactive subunit may influence IL-13 binding to its receptor complex. Thus, we propose that there are at least four forms of IL-13R.
Obiri
N I
NI
Laboratory of Molecular Tumor Biology, Division of Cellular and Gene Therapies, Food and Drug Administration, Center for Biologics Evaluation and Research, Bethesda, MD 20892, USA.
Leland
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P
Murata
T
T
Debinski
W
W
Puri
R K
RK
D036002:ADP Ribose Transferases; D015703:Antigens, CD / Q000276:immunology*; D001427:Bacterial Toxins; D001667:Binding, Competitive / Q000276:immunology; D002448:Cell Adhesion / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D005098:Exotoxins / Q000276:immunology; D006801:Humans; D053661:Interleukin-13 Receptor alpha1 Subunit; D018448:Models, Immunological; D009928:Organ Specificity / Q000276:immunology; D011485:Protein Binding / Q000276:immunology; D018123:Receptors, Interleukin / Q000276:immunology*; D053660:Receptors, Interleukin-13; D019948:Receptors, Interleukin-4; D014407:Tumor Cells, Cultured; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D015703:Antigens, CD; D001427:Bacterial Toxins; D005098:Exotoxins; D053661:Interleukin-13 Receptor alpha1 Subunit; D018123:Receptors, Interleukin; D053660:Receptors, Interleukin-13; D019948:Receptors, Interleukin-4; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C508181:IL13RA1 protein, human