Cell proliferation is regulated in several contexts, for example during development, tissue differentiation, wound healing and immune responses. In mammalian cells, proliferative signals lead to the activation of a protein kinase cascade, resulting in the phosphorylation of two closely related Mitogen-Activated Protein Kinases (MAPK’s) ERK1 and ERK2 of 44 kDa and 42 kDa, respectively. When activated, ERK’s form dimers that translocate to the nucleus where they phosphorylate several classes of transcription factors which are involved in the up-regulation of immediate early genes. As such, ERK1 and ERK2 represent a paradigm for a growing family of proline-directed protein kinases that mediate entry, progression and exit from the cell cycle in diverse eukaryotic cells. These enzymes function within highly conserved cascade of sequentially activating protein kinases that transduce signals from diverse extracellular stimuli. Alternative splice transcript variants encoding different protein isoforms have been described. ERK1 and ERK2 are phosphorylated within the activation loop on both a Threonine and a Tyrosine residue (within a Thr-Glu-Tyr motif) by MEKs (MAPK/ERK kinases), thereby greatly elevating the activity of ERK1&2. In vertebrates the mitogen-induced sequential activation of the kinases Raf1->Mek1->Erk2->Rsk occurs via the G-protein Ras.
MAP kinase 1, MAP kinase 2, p42-MAPK
Anti-Erk2 antibody was prepared by repeated immunizations with an Erk2 containing fusion protein. The epitope maps near the carboxy-terminus of human p42 MAP Kinase (ERK2) protein. The epitope is identical to the corresponding sequence in mouse and differs from the rat sequence by a single, conservative amino acid substitution.