Molecular Cloning And Tissue Distribution Of CD4and TGF-β1from Lateolabrax Japonicus

CD4is a transmembrane glycoprotein fundamental for cell-mediated immunity. It actas a T cell coreceptor increases the avidity of association between a T cell and an antigen-presenting cell by interacting with portions of the complex between MHC class II and TRmolecules. TGF-β is a highly conserved pleiotropic cytokine.In this paper we report thecDNA cloning, expression and three dimensional structural analysis of CD4fromLateolabrax japonicus, and express the protein of CD4’ extracellular region in E.coli. Also,weprestented the Lateolabrax japonicus’s TGF-β full-length cDNA. The Lateolabrax japonicusCD4cDNA consists of2217bp (174bp5’-UTR,630bp3’-UTR and1413bp ORF) thattranslates in one reading frame to give the entire molecule containing470amino acids. Theanalysis of the sequence shows the presence of four putative Ig-like domains and that somefundamental structural features, like a disulphide bond in domain D2and the CXCsignalling motif in the cytoplasmic tail, are conserved from Lateolabrax japonicus tomammals.The research of Lateolabrax japonicus’s CD4three dimensional structuralindicates that the3D structures of human and Lateolabrax japonicus are similar. It has twostructural domain: D1and D2, D1domain is characterized by an immunoglobulin-like beta-sandwich made of nine beta-strands; while The D2domain is a “C2-like domain”. Semi-quantitative RT-PCR was used to characterize the expression of CD4in nine tissuesincluding muscle, heart, brain, gill, liver, intestine, kidney, adipose tissue and spleen. Theresults showed that CD4is mainly expressed in the intestine. The Lateolabrax japonicus TGF-β1cDNA consists of2469bp(26bp5’-UTR,1183bp3’-UTR and1260bp ORF) thattranslates in one reading frame to give the entire molecule containing420amino acids.Thestructure and expression paettern of TGF-β is similar to those of other fish.