tailieunhanh - Báo cáo khoa học: Intrinsically active variants of all human p38 isoforms

The p38 mitogen-activated protein kinases are activated in response to var-ious extracellular signals in eukaryotic cells and play a critical role in the cellular responses to these signals. The four mammalian isoforms (p38a, p38b, p38c, and p38d) are coexpressed and coactivated in the same cells. The exact role of each p38 isoform has not been entirely identified, in part due to the inability to activate each member individually. | ỊFEBS Journal Intrinsically active variants of all human p38 isoforms Michal Avitzour Ron Diskin Bilha Raboy Nadav Askari David Engelberg and Oded Livnah Department of BiologicalChemistry The Wolfson Centre for Applied StructuralBiology The Silberman Institute of Life Sciences The Hebrew University of Jerusalem Israel Keywords active mutants autophosphorylation mitogen-activated protein kinase p38 signal transduction Correspondence O. Livnah Department of Biological Chemistry The Institute of Life Sciences The Wolfson Centre for Applied Structural Biology The Hebrew University of Jerusalem Safra Campus Givat Ram Jerusalem 91904 Israel Fax 972 2 658 5793 Tel 972 2 658 6894 E-mail Received 12 October 2006 revised 7 December 2006 accepted 11 December 2006 doi The p38 mitogen-activated protein kinases are activated in response to various extracellular signals in eukaryotic cells and play a critical role in the cellular responses to these signals. The four mammalian isoforms p38a p38b p38y and p38ỗ are coexpressed and coactivated in the same cells. The exact role of each p38 isoform has not been entirely identified in part due to the inability to activate each member individually. This could be resolved by the use of intrinsically active mutants. Based on previous studies on yeast p38 Hog1 Bell M Capone R Pashtan I Levitzki A Engel-berg D 2001 J Biol Chem 276 25351-2538 and human p38a Diskin R Askari N Capone R Engelberg D Livnah O 2004 J Biol Chem 279 47040-47049 we have generated intrinsically active p38b p38y and p38ỗ mutants. In addition we have identified a new activating mutation site in p38a. Most of the activating mutations are located in the L16 loop in which conformational changes were shown to induce activation. We show that these changes impose substantial autophosphorylation activity providing a mechanistic explanation for the intrinsic activity of the mutants. The new active variants maintain .