If the plug-in named ChemScape Chime is properly installed on your computer, you should see a rotating 3D HIV-Tat molecule. The molecule can be moved by clicking it with the left button of your mouse and its characteristics, including automatic rotation, can be modified by clicking it with the right button.
To download the plug-in: 
.
HIV-1 Tat protein, released from HIV infected cells, may acts as a pleiotropic heparin-binding growth factor. On this basis, extracellular Tat has been implicated in the pathogenesis of AIDS and of AIDS-associated pathologies.
Here we demonstrate that the heparin analogue pentosan polysulfate (PPS) inhibits the interaction of gluthatione-S-transferase (GST)-Tat protein with heparin immobilized to a BIAcore sensor chip. Competition experiments showed that Tat/PPS interaction occurs with high affinity (Kd = 9.0 nM). Also, GST-Tat prevents the binding of 3H-heparin to GST-Tat immobilized to gluthatione-agarose beads.
In vitro, PPS inhibits GST-Tat internalization and, consequently, HIV-1 long terminal repeat (LTR) transactivation in HL3T1 cells. Also, PPS inhibits cell-surface interaction and mitogenic activity of GST-Tat in murine adenocarcinoma T53 Tat-less cells. In all the assays, PPS exerts its Tat-antagonist activity with an ID50 equal to approximately 1.0 nM.
In vivo, PPS inhibits the neovascularization induced by GST-Tat or by Tat-overexpressing T53 cells in the chick embryo chorioallantoic membrane.
In conclusion, PPS binds Tat protein and inhibits its cell surface interaction, internalization, and biological activity in vitro and in vivo. PPS may represent a prototypic molecule for the development of novel Tat antagonists with therapeutic implications in AIDS and AIDS-associated pathologies, including Kaposi’s sarcoma.
J. Biol. Chem. 2001 276 :22420-22425
