Xenopus oocytes exhibit a receptor-evoked Cl- current that is mediated through the activation of phospholipase C (PLC) and release of intracellular Ca2+. The identity of PLC(s) mediating this effect is unknown. We have cloned cDNAs encoding a new form of PLC-β from a Xenopus oocyte cDNA library. The Xenopus PLC-β has substantial (33-64%) homology with mammalian β1, β2, β3, and β4 phospholipase C and is closest to PLC-β3, with 64% identity and 80% similarity. Injection of antisense oligonucleotides to a specific region of Xenopus PLC-β results in degradation of its mRNA and significantly reduces Cl- currents evoked by both endogenous angiotensin receptors and expressed mammalian α(1b)-adrenergic receptors and M1- muscarinic receptors as compared to responses in sense oligonucleotide- injected oocytes. Inhibition of the M1-muscarinic response by antisense oligonucleotides was nonadditive with pertussis toxin inhibition. PLC antisense oligonucleotide-injected oocytes show Cl- current responses to IP3 that are indistinguishable from sense oligonucleotide-injected oocytes. Since the receptor responses are pertussis toxin-sensitive, we conclude that we have isolated a new form of PLC-β involved in the pertussis toxin- sensitive receptor stimulation of the Ca2+ activated Cl- current in Xenopus oocytes.
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - 1993|