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p38-2, a novel mitogen-activated protein kinase with distinct properties.

Mitogen-activated protein (MAP) kinases are involved in many cellular processes. Here we describe the cloning and characterization of a new MAP kinase, p38-2. p38-2 belongs to the p38 subfamily of MAP kinases and shares with it the TGY phosphorylation motif. The complete p38-2 cDNA was isolated by polymerase chain reaction. It encodes a 364-amino acid protein with 73% identity to p38. Two shorter isoforms missing the phosphorylation motif were identified. Analysis of various tissues demonstrated that p38-2 is differently expressed from p38. Highest expression levels were found in heart and skeletal muscle. Like p38, p38-2 is activated by stress-inducing signals and proinflammatory cytokines. The preferred upstream kinase is MEK6. Although p38-2 and p38 phosphorylate the same substrates, the site specificity of phosphorylation can differ as shown by two-dimensional phosphopeptide analysis of Sap-1a. Additionally, kinetic studies showed that p38-2 appears to be about 180 times more active than p38 on certain substrates such as ATF2. Both kinases are inhibited by a class of pyridinyl imidazoles. p38-2 phosphorylation of ATF2 and Sap-1a but not Elk1 results in increased transcriptional activity of these factors. A sequential kinetic mechanism of p38-2 is suggested by steady state kinetic analysis. In conclusion, p38-2 may be an important component of the stress response required for the homeostasis of a cell.

Pubmed ID: 9235954


  • Stein B
  • Yang MX
  • Young DB
  • Janknecht R
  • Hunter T
  • Murray BW
  • Barbosa MS


The Journal of biological chemistry

Publication Data

August 1, 1997

Associated Grants


Mesh Terms

  • Activating Transcription Factor 2
  • Adult
  • Amino Acid Sequence
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Cyclic AMP Response Element-Binding Protein
  • DNA, Complementary
  • Humans
  • Kinetics
  • MAP Kinase Kinase 6
  • MAP Kinase Kinase Kinase 1
  • Molecular Sequence Data
  • Phosphorylation
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • RNA, Messenger
  • Transcription Factors