Activation of Early Gene Expression in T Lymphocytes by Oct-1 and an Inducible Protein, OAP ⁴⁰

After antigenic stimulation of T lymphocytes, genes essential for proliferation and immune function, such as the interleukin-2 (IL-2) gene, are transcriptionally activated. In both transient transfections and T lymphocyte-specific in vitro transcription, the homeodomain-containing protein Oct-1 participated in the inducible regulation of transcription of the IL-2 gene. Oct-1 functioned in this context with a 40-kilodalton protein called Oct-1-associated protein (OAP40). In addition to interacting specifically with DNA, OAP40 reduced the rate of dissociation of Oct-1 from its cognate DNA-binding site, suggesting that a direct interaction exists between Oct-1 and OAP40.