LYSOPHOSPHATIDIC ACID-INDUCED ACTIVATION OF PROTEIN SER THR KINASES IN CULTURED RAT 3Y1 FIBROBLASTS - POSSIBLE INVOLVEMENT IN RHO-P21-MEDIATED SIGNALING/

Renaturation kinase assay was used to detect protein kinases activated by lysophosphatidic acid (LPA) in cultured rat 3Y1 fibroblasts. LPA a ctivated several Ser/Thr protein kinases with apparent molecular weigh ts of 145K, 85K, 64-65K (a doublet), and 60K (each named p145, p85, p6 4165 and p60, respectively) in addition to p43 mitogen activated prote in (MAP)kinase. Experiments using pertussis toxin and botulinum C3 exo enzyme showed that p145, p85, and p64165 kinases were activated by a p ertussis toxin-insensitive rho p21-dependent pathway and that the acti vation of MAP-kinase was mediated by both the pertussis toxin-sensitiv e rho p21-independent and the pertussis toxin-insensitive rho p21-depe ndent pathways.