Abstract: The invention relates to a cellular protein which is specific and has high affinity for nucleic acid sequences characteristic of an intact TAR RNA loop sequence of the HIV LTR TAR region. The invention also relates to a protein preparation having a protein of about 185 kD that is isolated from a mammalian cell nuclear extract preparation, most specifically a HeLa cell extract that is purified between 1,000-10,000 fold. The protein of about 185 kD is shown to regulate HIV viral gene expression by binding a TAR RNA region of an HIV LTR template, in the presence of a cofactor fraction (including at least a -100 kD cofactor), and a tat protein. A route for the development of immunodiagnostics for AIDS and related disorders may also be provided given the specific and high affinity of TRP-185 for HIV RNA.

Abstract: The invention relates to a cellular protein which is specific and has high affinity for nucleic acid sequences characteristic of an intact TAR RNA loop sequence of the HIV LTR TAR region. The invention also relates to a between 1,000-10,000-fold purified, about 185 kD protein preparation isolated from a mammalian cell nuclear extract preparation, most specifically a HeLa cell extract. The about 185 kD protein is shown to regulate HIV viral gene expression by binding a TAR RNA region of an HIV LTR template, in the presence of a cofactor fraction (including at least a.about.100 kD cofactor), and a tat protein. The TRP-185, having a molecular weight of about 185 kD protein may also provide a research tool in the study of viral and cellular gene expression. A route for the development of immunodiagnostics for AIDS and related disorders may also be provided given the specific and high affinity of TRP-185 for HIV RNA.