Mitogen-activated protein kinase kinase 1–Kinase suppressor of Ras 1 complex (MEK1–KSR1 complex) (MEK1–KSR1)

The Mitogen-activated protein kinase kinase 1–Kinase suppressor of Ras 1 (MEK1–KSR1) complex is a pivotal regulatory assembly in the Ras-Raf-MEK-ERK signaling cascade. KSR1 functions as a molecular scaffold that physically organizes the pathway components, specifically sequestering MEK1 to facilitate its activation by RAF kinases (UniProt Q8IVH8; Lavoie et al., 2018). This complex is a major driver in various malignancies, especially those harboring KRAS, NRAS, or BRAF mutations, where it promotes aberrant cell proliferation and survival (PubMed: 32054751). Therapeutic targeting of the complex has evolved with the discovery that certain MEK inhibitors, such as trametinib, exhibit enhanced efficacy by binding to MEK1 specifically when it is complexed with KSR1 (Khan et al., 2020). Furthermore, novel small molecules are being developed to directly inhibit KSR1 or disrupt the MEK-KSR interface to overcome resistance to standard MAPK inhibitors (ClinicalTrials.gov). Understanding the structural biology of this complex is crucial for the design of precision medicines in oncology. The complex's role in feedback loops and its ability to modulate signal intensity make it a sophisticated target for overcoming adaptive resistance in cancer therapy.

Other names

MAP2K1–KSR1 complexMEK–KSR complexMEK1–KSR scaffold complexMEK1–KSR1 signaling unit

Allosteric inhibition of MEK1 within the KSR1 scaffold and stabilization of the inactive MEK–KSR complex to prevent ERK activation (Khan et al., 2020; Lavoie et al., 2018).