RSK1 Protein, Human (sf9)

RSK1, a serine/threonine-protein kinase, functions downstream of ERK (MAPK1/ERK2 and MAPK3/ERK1) signaling and plays a crucial role in mediating mitogenic and stress-induced cellular responses. RSK1 orchestrates the activation of transcription factors such as CREB1, ETV1/ER81, and NR4A1/NUR77, contributing to cellular proliferation, survival, and differentiation. Through its intricate involvement in the mTOR signaling pathway, RSK1 regulates translation by phosphorylating RPS6 and EIF4B, facilitating the assembly of pre-initiation complexes and enhancing cap-dependent translation. Furthermore, RSK1 exerts its influence on various cellular processes, including inhibiting the pro-apoptotic functions of BAD and DAPK1, promoting cell survival, and regulating cell cycle progression by phosphorylating CDKN1B. In response to insulin, RSK1 indirectly modulates gene transcription by phosphorylating GSK3B, and in the mTOR nutrient-sensing pathway, it phosphorylates TSC2 and RPTOR, influencing mTORC1 activity. Additionally, RSK1 participates in the feedback regulation of mTORC1 and mTORC2 by phosphorylating DEPTOR. Notably, during microbial infections, RSK1 is implicated in promoting the late transcription and translation of viral lytic genes in Kaposi's sarcoma-associated herpesvirus/HHV-8 infection when constitutively activated.