[PDF][PDF] C. elegans ksr-1 and ksr-2 have both unique and redundant functions and are required for MPK-1 ERK phosphorylation

M Ohmachi, CE Rocheleau, D Church, E Lambie… - Current biology, 2002 - cell.com
M Ohmachi, CE Rocheleau, D Church, E Lambie, T Schedl, MV Sundaram
Current biology, 2002cell.com
Abstract Kinase Suppressor of Ras (KSR) is a conserved protein that positively regulates
Ras signaling and may function as a scaffold for Raf, MEK, and ERK [1]. However, the
precise role of KSR is not well understood, and some observations have suggested that
KSR might act in a parallel pathway. In C. elegans, ksr-1 is only required for a specific Ras-
mediated process (sex myoblast migration) and is a nonessential positive regulator of other
Ras-mediated developmental events [2, 3]. We report the existence of a second C. elegans …
Abstract
Kinase Suppressor of Ras (KSR) is a conserved protein that positively regulates Ras signaling and may function as a scaffold for Raf, MEK, and ERK [1]. However, the precise role of KSR is not well understood, and some observations have suggested that KSR might act in a parallel pathway. In C. elegans, ksr-1 is only required for a specific Ras-mediated process (sex myoblast migration) and is a nonessential positive regulator of other Ras-mediated developmental events [2, 3]. We report the existence of a second C. elegans ksr gene, ksr-2, which is required for Ras-mediated signaling during germline meiotic progression and functions redundantly with ksr-1 during development of the excretory system, hermaphrodite vulva, and male spicules. Thus, while the ksr-1 and ksr-2 genes are individually required only for specific Ras-dependent processes, together these two genes appear necessary for most aspects of Ras-mediated signaling in C. elegans. The finding that ksr-2; ksr-1 double mutants have strong ras-like phenotypes and severely reduced or absent levels of diphosphorylated MPK-1 ERK strongly supports models where KSR acts to promote the activation or maintenance of the Raf/MEK/ERK kinase cascade.
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