A receptor binding domain of mouse interleukin-4 defined by a solid-phase binding assay and in vitro mutagenesis.

摘要: Interleukin 4 (IL-4) is a potent, pleiotropic lymphokine that affects variety of cells, especially those hematopoietic origin. Although murine and human IL-4 are homologous proteins, they display species specificity in which acts only upon mouse cells. We have used mutagenesis strategy to define both the structural determinants this receptor binding domain IL-4. To do this, we developed convenient solid-phase assays for IL-4, each utilizing receptor-immunoglobulin fusion proteins alkaline phosphatase-tagged ligands. These were employed assess activities wild type mutant forms In separate biological assay, measured ability version induce proliferation cultured T-cell line. By replacing regions with segments found amino-terminal 16 residues carboxyl-terminal 20 required species-specific as well proliferation. A major portion amino acid sequence between these can be substituted without loss or activity. Further, alanine-scanning revealed specific amino- (Glu-12, Ile-14, Leu-104, Asp-106, Phe-107, Leu-111) bear side chains critical function. An analysis region its comparison other related cytokines suggest an evolutionary conservation functional features.