Additionally, numerous pathological conditions are also associated with the Tat protein. For example, it inhibits phagocytosis in macrophages by binding to phosphoinositol-4,5-biphosphate (PI4,5P2) on cell membranes and alters the activity of potassium channels in cardiomyocytes . Some others involve triggering neurodegeneration , disrupting the blood-brain barrier , and inducing apoptosis in T cells . In summary, this protein performs many tasks in the extracellular and intracellular milieu and with that, it rightly has earned the reputation of being the main viral toxin of the HIV-1 virus .