TALL-1 is a novel member of the TNF family that is down-regulated by mitogens.
Members of the tumor necrosis factor (TNF) family play important roles in modulation of immune responses. We describe the identification and cloning of a novel TNF family member that has been designated as TALL-1. TALL-1 is a 285-amino acid type II transmembrane protein. Its carboxy terminus shares approximately 35% sequence identity with the recently identified APRIL and approximately 20-25% with TNF, FasL, TRAIL, and lymphotoxin-alpha, suggesting that TALL-1 and APRIL belong to a subfamily of the TNF family of ligands. Northern blot analysis suggests that TALL-1 is expressed abundantly in peripheral blood leukocytes and weakly in spleen but is barely detectable in all other tissues examined. Reverse transcriptase-polymerase chain reaction analysis indicates that TALL-1 is specifically expressed in monocytes and macrophages but is undetectable in T and B lymphocytes. Furthermore, TALL-1 expression is dramatically down-regulated by phorbol myristate acetate/ionomycin.
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National Jewish Medical and Research Center, University of Colorado Health Sciences Center, Department of Immunology, Denver 80206, USA. shuh@njc.org
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D000595:Amino Acid Sequence; D000818:Animals; D053264:B-Cell Activating Factor; D003001:Cloning, Molecular; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D008024:Ligands; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D008934:Mitogens / Q000494:pharmacology*; D008969:Molecular Sequence Data; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics
D053264:B-Cell Activating Factor; D008024:Ligands; D008565:Membrane Proteins; D008934:Mitogens; C114631:TNFSF13 protein, human; C505719:TNFSF13B protein, human; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D014409:Tumor Necrosis Factor-alpha