Site-directed mutagenesis reveals the importance of disulfide bridges and aromatic residues for structure and proliferative activity of human interleukin-4.
Mutant proteins (muteins) of human Interleukin-4 (IL4) were constructed by means of in vitro mutagenesis. The muteins were expressed in E. coli, submitted to a renaturation and purification protocol and analysed for biological activity. Exchange of the cysteines at either position 46 or 99 which form one of the three disulfide bridges resulted in a nearly complete loss of biological activity and an unstable protein. The exchange of tyrosine 124 also inactivated the protein, while a mutation of tyrosine 56 left some residual activity. Exchange of the other four cysteines or of the single tryptophane had smaller effects.
Kruse
N
N
Physiologisch-Chemisches Institut der Universität Würzburg, Germany.
Lehrnbecher
T
T
Sebald
W
W
D001483:Base Sequence; D003545:Cysteine / Q000737:chemistry; D004247:DNA; D004220:Disulfides / Q000737:chemistry*; D006801:Humans; D015847:Interleukin-4 / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed
D004220:Disulfides; D015847:Interleukin-4; D004247:DNA; D003545:Cysteine