The purification and cloning of MEK1: A mitogen-activated protein (MAP) kinase activator

摘要: MAP/ERK (Mitogen Activated Protein/Extracellular Signal-Regulated Kinase) kinases are a family of serine/threonine kinases that are rapidly activated in response to mitogens, cytoplasmic oncogene products and certain extracellular stimuli. In addition to several substrates whose phosphorylation by MAP kinase causes unknown effects, MAP kinase phosphorylates and activates at least three other enzymes, pp90 (Ribosomal S6 Kinase), MAPKAP 2 (heat shock protein kinase) and PLA (Phospholipase A2). The discovery that MAP kinase could partially activate pp90 in vitro was the first evidence of a mitogen-induced kinase cascade. The fact that MAP kinases require threonine and tyrosine phosphorylation for activity suggested that they serve as integration points for tyrosine as well as serine/threonine kinase pathways. Alternatively, an upstream activator may have been a stimulator of …