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Pseudokinase domain of Kinase Suppressor of Ras The pseudokinase domain shows similarity to protein kinases but lacks crucial residues for catalytic activity. KSR is a scaffold protein that functions downstream of Ras and upstream of Raf in the Extracellular signal-Regulated Kinase (ERK) pathway that regulates many cellular processes including cycle regulation, proliferation, differentiation, survival, and apoptosis. KSR proteins regulate the assembly and activation of the Raf/MEK/ERK module upon Ras activation at the membrane by direct association of its components. They are widely regarded as pseudokinases, but there is some debate in this designation as a few groups have reported detecting kinase catalytic activity for KSRs, specifically KSR1. Vertebrates contain two KSR proteins, KSR1 and KSR2. The KSR subfamily is part of a larger superfamily that includes the catalytic domains of other protein kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
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