The gene encoding the Act-2 cytokine. Genomic structure, HTLV-I/Tax responsiveness of 5' upstream sequences, and chromosomal localization.

Act-2 is a cytokine that belongs to a superfamily of structurally related proteins. Act-2 expression is rapidly induced in T cells, B cells, and monocytes upon mitogenic stimulation. The Act-2 genomic locus is on chromosome 17q. The exons and exon/intron splice junctions have been sequenced, as have the sequences upstream of exon 1. A classical TATA box is located immediately upstream of the transcription initiation site. The upstream sequences possess promoter activity and can be functionally activated after treatment of Jurkat T cells with phythohemagglutinin plus phorbol myristrate acetate. In addition, Act-2 promoter chloramphenicol acetyltransferase constructs are expressed in human T cell lymphotropic virus type I (HTLV-I)-infected MT-2 cells and in Jurkat cells which can be induced to express the transactivator gene (tax) product of HTLV-I.