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TY - JOUR AU - Sturgill, Thomas W. AU - Ray, L. Bryan AU - Erikson, Eleanor AU - Maller, James L. PY - 1988 DA - 1988/08/01 TI - Insulin-stimulated MAP-2 kinase phosphorylates and activates ribosomal protein S6 kinase II JO - Nature SP - 715 EP - 718 VL - 334 IS - 6184 AB - Ribosomal protein S6 is a component of the eukaryotic 40S ribosomal subunit that becomes phosphorylated on multiple serine residues in response to a variety of mitogens, including insulin, growth factors, and transforming proteins of many oncogenic viruses. Recently, an activated S6 kinase (S6 KII) has been purified to homogeneity from Xenopus eggs1, and characterized immunologically2 and at the molecular level3. Purified S6 KII can be deactivated in vitro by incubation with either protein phosphatase 1 or protein phosphatase 2A. Reactivation and phosphorylation of S6 KII occurs in vitro with an insulin-stimulated micro-tubule-associated protein-2 (MAP-2) protein kinase which is itself a phosphoprotein that can be deactivated by protein phosphatase 2A. These studies suggest that a step in insulin signalling involves sequential activation by phosphorylation of at least two serine/threonine protein kinases. SN - 1476-4687 UR - https://doi.org/10.1038/334715a0 DO - 10.1038/334715a0 ID - Sturgill1988 ER -