Human protein: protein HEXIM1
Human protein sequence: MAEPFLSEYQHQPQTSNCTGAAAVQEELNPERPPGAEERVPEEDSRWQSRAFPQLGGRPGPEGEGSLESQPPPLQTQACPESSCLREGEKGQNGDDSSAGGDFPPPAEVEPTPEAELLAQPCHDSEASKLGAPAAGGEEEWGQQQRQLGKKKHRRRPSKKKRHWKPYYKLTWEEKKKFDEKQSLRASRIRAEMFAKGQPVAPYNTTQFLMDDHDQEEPDLKTGLYSKRAAAKSDDTSDDDFMEEGGEEDGGSDGMGGDGSEFLQRDFSETYERYHTESLQNMSKQELIKEYLELEKCLSRMEDENNRLRLESKRLGGDDARVRELELELDRLRAENLQLLTENELHRQQERAPLSKFGD

HIV protein: Tat
Interaction type: competes with
Description: MAQ1 complexes with 7SK RNA and cyclin T1 and competes with the binding of Tat to cyclin T1, suggesting the TAR RNA/Tat lentivirus system has evolved to subvert the cellular 7SK RNA/MAQ1 system
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: competes with
Description: HIV-1 Tat competes with Hexim1 (residues 255-359) for cyclin T1 binding, thus releasing P-TEFb from the inactive complex to stimulate the transcription of HIV-1 gene expression
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: inhibited by
Description: HIV-1 Tat transactivation is effectively inhibited by co-expression of HEXIM1 or its paralog HEXIM2; HEXIM1 expression specifically represses transcription mediated by the direct activation of P-TEFb through Tat recruitment of CycT1
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: relocalizes
Description: HIV-1 Tat displaces HEXIM1 from Cyclin T1 in the context of the native 7SK snRNP by interacting with the Cyclin T1-binding domain (amino acid 255-359) of HEXIM1
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: competes with
Description: HIV-1 Tat competes with HEXIM1 for binding to 7SK RNA and inhibits the formation of the P-TEFb-HEXIM1-7SK complex. Tat binds to nucleotides 10-48 of 7SK RNA
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: interacts with
Description: A La-related protein, LARP7, is associated with P-TEFb, HEXIM1/2, MEPCE, and 7SK RNA in a large stable complex form. Knockdown of LARP7 decreases the steady-state level of 7SK, but increases free P-TEFb and enhances Tat-mediated transcription
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: interacts with
Description: CDK11 depletion reduces protein expression of CDK9 and HEXIM1 and Tat transactivation of HIV-1 provirus
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: competes with
Description: TAR binds Tat and P-TEFb as it emerges on the nascent transcript, competitively displacing the inhibitory 7SK snRNP (HEXIM1 and LARP7) and activating the P-TEFb kinase
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: induces release of
Description: HIV-1 Tat-mediated release of P-TEFb from the 7SK sn RNP results in a conformational change in 7SK RNA and release of HEXIM1 from the complex
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: competes with
Description: HIV-1 Tat directly interacts with human 7SK snRNA in living cells. The 5' hairpin of human 7SK snRNA carries a conserved Tat-binding element and two HEXIM1-binding sites. Tat competes with HEXIM1 for 7SK snRNA binding
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: competes with
Description: AFF1 enhances the affinity of HIV-1 Tat for CycT1, which competitively dissociates HEXIM1 and is responsible for AFF1's promotion of Tat's extraction of CDK9/CycT1 from 7SK snRNP
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE

HIV protein: Tat
Interaction type: interacts with
Description: CDK9-CycT1-AFF1 is stimulated by HIV-1 Tat and transferred as a single complex unit to BRD4 upon stress-induced disruption of AFF1-containing 7SK snRNP (HEXIM1, MEPCE, LARP7, 7SK RNA, CDK9, CycT1, and AFF1)
HIV protein sequence: MEPVDPRLEPWKHPGSQPKTACTNCYCKKCCFHCQVCFITKALGISYGRKKRRQRRRAHQNSQTHQASLSKQPTSQPRGDPTGPKE