Kinase Suppressor Of Ras 2 (KSR2)

The predicted 829-amino acid protein has a molecular mass of approximately 105 kD. Similar to KSR1 , KSR2 appears to lack the CA1 domain. KSR2 shares 61% amino acid identity with KSR1. Northern blot analysis revealed expression mainly in kidney and brain. Coimmunoprecipitation studies showed that KSR2 interacted with components of the MAPK pathway, including RAF (RAF1), MEK (MAP2K1), and ERK (MAPK3).Cotransfection of KSR2 with COT in HEK-293T cells lead to reduced COT-mediated ERK activation in a dose-dependent manner; however, RAF-mediated ERK activation was not significantly attenuated by coexpression with KSR2, suggesting that the effect is selective. Luciferase reporter assays showed that KSR2 inhibited COT-induced NF-kappa-B activation but did not inhibit IKKB-mediated NF-kappa-B activation.