Transcriptional regulator which functions as a general RNA polymerase II transcription inhibitor (, ). Core component of the 7SK RNP complex: in cooperation with 7SK snRNA sequesters P-TEFb in a large inactive 7SK snRNP complex preventing RNA polymerase II phosphorylation and subsequent transcriptional elongation (, ).
Subcellular locations: Nucleus
Ubiquitously expressed with higher expression in testis. HEXIM1 and HEXIM2 are differentially expressed.