Cross-species PCR cloning of gerbil (Meriones unguiculatus) interleukin-2 cDNA and its expression in COS-7 cells.

A cDNA clone of the gerbil interleukin-2 (IL-2) gene was isolated by cross-species PCR cloning, and demonstrated to produce a functional gerbil IL-2 protein when inserted in the eucaryotic expression vector pSV-SPORT1 and transfected into COS-7 monkey cells. The open reading frame codes for a polypeptide of 155 amino acid residues with a molecular weight (MW) of 17,601 which includes a putative signal peptide. The mature gerbil IL-2 is deduced to contain 135 amino acid residues and has a calculated MW of 15,496. Culture supernatant of COS-7 cells transfected with pSV-SPORT1-GIL-2, but not pSV-SPORT1 stimulates the proliferation of the IL-2 dependent murine CTLL-2 cells. Molecular characteristics of gerbil IL-2 have been compared with IL-2 of mouse, rat, human, bovine, ovine and porcine origin. The mature form of gerbil IL-2 is similar in molecular weight to all species except the mouse. A N-glycosylation site present in bovine, ovine and porcine IL-2 respectively, is absent in gerbil. Three Cys residues are conserved in all compared mature IL-2 molecules. In these comparisons, gerbil IL-2 has highest identity with rat IL-2 for both nucleotide and amino acid sequence.