Chemoattractants induce tyrosine phosphorylation of ERK2 in Dictyostelium discoideum by diverse signalling pathways.
Two homologues of mitogen-activated protein kinases have been identified in Dictyostelium discoideum (ERK1 and EKR2). We here demonstrate transient tyrosine phosphorylation of ERK2 in response to the chemoattractants cAMP and folic acid that correlates with activity. To investigate the signalling pathways, we studied the response in strains with altered cAMP-dependent protein kinase (PKA) status. The degree of cAMP-induced ERK2 tyrosine phosphorylation was increased in cells overexpressing PKA activity but no such increase was observed in the response to folic acid. Our observations suggest that cAMP-induced ERK2 tyrosine phosphorylation is positively modulated by a PKA-regulated step which is not involved in the response to folic acid, suggesting the presence of diverse signalling pathways leading to ERK2 activation.
Kosaka
C
C
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
Pears
C J
CJ
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D002630:Chemotactic Factors; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004023:Dictyostelium / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D004789:Enzyme Activation; D005492:Folic Acid / Q000494:pharmacology; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1; D019000:Phosphotyrosine; D015398:Signal Transduction
D002630:Chemotactic Factors; D019000:Phosphotyrosine; D005492:Folic Acid; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1