CDK7

CDK7 (cyclin-dependent kinase 7) functions as a dual-regulatory kinase that coordinates cell-cycle progression and RNA polymerase II-dependent transcription through its activity within the CDK-activating kinase (CAK) complex and the general transcription factor TFIIH complex^[1][2][3]. CDK7 phosphorylates and activates multiple cell-cycle CDKs, including CDK1, CDK2, CDK4, and CDK6, thereby linking transcriptional control to cell-cycle regulation^[1][4]. Mechanistically, TFIIH-associated CDK7 phosphorylates the C-terminal domain (CTD) of RNA polymerase II and promotes transcription initiation, promoter clearance, and productive promoter escape^[2][5][6]. CDK7 further regulates transcriptional programs through phosphorylation-dependent control of transcription-associated kinases and RNA processing factors, supporting coordinated gene expression in proliferating cells^[2]. In disease models, aberrant CDK7 activity is associated with tumor cell proliferation and transcriptional dependency, making CDK7 a relevant target for cancer research and therapeutic intervention^[1][7]. Compared with related CDK family members that primarily regulate discrete cell-cycle transitions, CDK7 uniquely combines CAK activity with direct transcriptional regulation through TFIIH, establishing a distinct functional position within the CDK network^[4][6]. For experimental applications, selective CDK7 inhibitors have enabled mechanistic dissection of transcription initiation, RNA polymerase II dynamics, and transcriptional kinase signaling, supporting their broad use in functional genomics and oncology research^[2][5].