A low molecular weight factor from dividing cells activates phospholipase D in caveolin-enriched membrane microdomains.
Phospholipase D (PLD) activity is elevated in Ras-transformed NIH 3T3 cells. This difference in PLD activity between Ras-transformed and nontransformed parental cells disappeared in isolated membranes from these cells. In reconstitution experiments, heat-denatured cytosolic fractions from Ras-transformed, but not parental, NIH 3T3 cells elevated PLD activity in isolated membranes. This heat-resistant PLD-stimulating activity from the Ras-transformed cells was sensitive to proteases and passed through a 1-kDa MW cutoff membrane, suggesting that the factor is a peptide of less than 10 amino acids. The ability of this PLD-stimulating factor, designated PLD-SF, to elevate PLD activity in isolated membranes was restricted to the caveolin-enriched light membranes, where many signaling molecules are localized. PLD-SF was also elevated in v-Src- and v-Raf-transformed cells and in serum-stimulated NIH 3T3 cells. PLD-SF was detected in a variety of rat tissues but was highest in testes, where a large percentage of cells are dividing. A similar low molecular weight PLD-stimulating activity was found in actively dividing, but not stationary yeast, cells. The data here provide evidence for a highly conserved PLD-stimulating peptide that is elevated in response to mitogenic stimuli.
Bychenok
S
S
Department of Biological Sciences, Hunter College of The City University of New York, New York, NY 10021, USA.
Foster
D A
DA
D016475:3T3 Cells; D000818:Animals; D001685:Biological Factors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D051242:Caveolin 1; D022461:Caveolins; D002455:Cell Division; D002458:Cell Fractionation; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D003600:Cytosol / Q000737:chemistry; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D010739:Phospholipase D / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D012995:Solubility
D001685:Biological Factors; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D022461:Caveolins; D008565:Membrane Proteins; D010739:Phospholipase D; D016283:Proto-Oncogene Proteins p21(ras)