background:
Hexamethylene bis-acetamide inducible 1 (HEXIM1) and Hexamethylene bis-acetamide inducible 2 (HEXIM2) comprise a family of proteins which inhibit positive transcription elongation factor b (P-TEFb) through association with 7SK. P-TEFb is composed of a catalytic subunit, Cdk9, and either Cyclin T1 or T2 as a regulatory subunit. This complex regulates eukaryotic gene expression at the level of elongation. The SLCterminal domains of HEXIM proteins interact directly with each other. Via these domains, HEXIM1 and HEXIM2 form stable homo- and hetero-oligomers, which may aid in the formation of the 7SK small nuclear ribonucleic acid particle. Despite their similar functions, HEXIM1 and HEXIM2 exhibit distinct expression patterns in various established cell lines and human tissues.
Function:
Transcriptional regulator which functions as a general RNA polymerase II transcription inhibitor. In cooperation with 7SK snRNA sequesters P-TEFb in a large inactive 7SK snRNP complex preventing RNA polymerase II phosphorylation and subsequent transcriptional elongation. May also regulate NF-kappa-B, ESR1, NR3C1 and CIITA-dependent transcriptional activity.
Subunit:
Homooligomer and heterooligomer with HEXIM2; probably dimeric. Component of the 7SK snRNP complex at least composed of P-TEFb (composed of CDK9 and CCNT1/cyclin-T1), HEXIM1, HEXIM2, BCDIN3, SART3 proteins and 7SK and U6 snRNAs. Interacts with the N-CoR complex through NCOR1. Interacts with ESR1 and NR3C1. May interact with NF-kappa-B through RELA.
Subcellular Location:
Nucleus. Cytoplasm. Binds alpha-importin and is mostly nuclear.
Tissue Specificity:
Ubiquitously expressed with higher expression in placenta. HEXIM1 and HEXIM2 are differentially expressed. Expressed in endocrine tissues.
Similarity:
Belongs to the HEXIM family.
Database links:
Entrez Gene: 10614 Human
Entrez Gene: 192231 Mouse
Entrez Gene: 419608 Rat
Omim: 607328 Human
SwissProt: O94992 Human
SwissProt: Q8R409 Mouse
SwissProt: Q5M9G1 Rat
Unigene: 15299 Human
Unigene: 586945 Human
Unigene: 634944 Human
Unigene: 741758 Human
Unigene: 8763 Mouse
Unigene: 113703 Rat
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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