All issues > Volume 36(3); 1993

Case Report

J Korean Pediatr Soc. 1993;36(3):409-416. Published online March 15, 1993.

Characterization of the Novel Late T Cell Activation Proteins, 519 and 520

Dae-Yeol DY Lee¹, Alan M AM Krensky²

¹Department of Pediatrics, Chonbuk National University Medical School, Chonju, Korea
²Department of Pediatrics, Stanford University, Stanford, CA, USA

Abstract

The late T cell activation gene, 519, is expressed in antigen specific, growth factor dependent T cell lines and clones but not in T or B cell tumors, other hematopoietic cells, tonsil, muscle, lung, or liver. Resting peripheral blood ymphocytes(PBLs)express little or no 519mRNA, but levels increase dramatically 5~7 days after activation with alloantigen or mitoen. Four alternatively spliced transcripts of the gene exist. 520 cDNA, the predominate gene transcript, encodes a protein of 144 amino acids and has a potentially cleavable hydrophobic leader of 15 amino acids at the amino terminus. The 519 transcript encodes a 129 amino acid product. An polyclonal antiserum was produced by immunizing a rabbit with a synthetic peptide corresponding to the second hydrophobic region common to both 519 and 520. 14.3 and 15.5kD protein bands were immunoprecipitated(IP)from radiolabled in-vitro translated products, 519 and 520 respectively. A protein of 14.3kD was detected by IP of in vivo 35S cysteine and methionine radiolabled cytotoxic T lymphocytes(CTL) cells. Western blotting of lysates from a CTL line and a B cell tumor line revealed a distinct band at 14.3kD only in CTL lanes. Both CTL and peripheral blood lymphocytes expressed the greatest amount of 519/520 protein in cells 5~7 days after stimulation. Western blotting of differenctial centrifugation samples localized 519/520 protei to the granule layer. Comparison of 519/520 protein with other known proteins with other known protin sequences identified homology with surfactant associated and sphyngolipid activating proteins. A homologous gene(NKG5) is present in natural killer cells(NK). The increase in the amount of the 519/520 protein product in CTL and PBL parallel increases in mRNA expression. 519/520 and related gene products are present in CTL, PBL parallel increases in mRNA expression. 519/520 and related gene products are present in CTL, PBL and NK cells, have structural similarity with lipid associating proteins.

Keywords :Cytotoxic T lymhocyte, Peripheral blood lymphocyte, Late T cell activation protein, 519, 520