passages.id: split_8_test_1391_passage
passages.type: progene_text
passages.text: Human immunodeficiency virus , type 1 ( HIV - 1 ) , Tat activates elongation of RNA polymerase II transcription at the HIV-1 promoter through interaction with the cyclin T1 ( CycT1 ) subunit of the positive transcription elongation factor complex , P - TEFb .