title: Expressed sequence identification and characterization of the cDNA for interleukin-4 from the mitogen-stimulated lymphoid tissue of a marsupial, Macropus eugenii.
abstract: Very few cytokines that are important to the understanding of T helper cell function are characterized in marsupials. Expression of a 645 bp cDNA product that codes for a predicted Interleukin-4 peptide of 157 amino acids was detected in the lymph node tissues of Macropus eugenii, the tammar wallaby. Using Rapid Amplification of cDNA Ends, both 5'- and 3'-untranslated regions were identified and a polyadenylation signal and three mRNA instability motifs associated with secreted cytokine molecules were also present. The translated cDNA sequence has a putative signal peptide of 24 amino acids, a predicted secondary structure that is consistent with the short-chain alpha-helical cytokine family and 82% conservation of residues associated with the Interleukin-4 family sequence motif. Comparisons of wallaby nucleotide and predicted peptide sequences with the coding domains of other vertebrate species demonstrate the diversity within this gene family; with nucleotide and amino acid identities of 74% and 59% with opossum, 52% and 32% with human and 38% and 19% with chicken homologues respectively. Despite these differences in sequence conservation, the putative Macropus eugenii Interleukin-4 mature peptide contains conserved structural motifs and predicted receptor-binding residues that suggest that it may retain functional properties associated with this important Th2 cytokine in other mammals.
authors.affiliation: Marsupial Immunology Research Laboratory, Centre for Environmental Management, CQUniversity, Bruce Highway, Rockhampton, Queensland 4702, Australia. l.young@cqu.edu.au
authors.forename: Lauren
authors.initials: L
authors.lastname: Young
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D015847:Interleukin-4 / Q000737:chemistry / Q000235:genetics*; D008221:Lymphoid Tissue / Q000276:immunology; D007614:Macropodidae / Q000235:genetics* / Q000276:immunology*; D008322:Mammals / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D018418:Th2 Cells / Q000276:immunology
chemical_list: D018076:DNA, Complementary; D015847:Interleukin-4