Screening of enzymatic mechanisms possible involved in membrane fusion during exocytosis in Paramecium cells.
Microinjected alkaline phosphatase triggered exocytosis of trichocysts. Among a variety of inhibitors and stimulators interfering with fusogenic mechanism discussed in the literature, only phosphatase inhibitors inhibited exocytosis. Various other enzymes were also tested with a new in vitro system (Vilmart-Seuwen et al., 1986), but results were mostly negative. (The possible involvement of proteases remains questionable.) Positive results obtained with micro-injected alkaline phosphatase are in line with our previous results: (a) The occurrence of a cytochemical reaction for phosphatase activity precisely at fusion sites (Plattner et al., 1980); (b) the occurrence of protein dephosphorylation during exocytosis (Gilligan and Satir, 1982; Zieseniss and Plattner, 1985) and (c) the negative modulatory effect of ATP on exocytotic membrane fusion (Vilmart-Seuwen et al., 1986).
D000469:Alkaline Phosphatase / Q000494:pharmacology*; D000818:Animals; D002474:Cell-Free System; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis; D066298:In Vitro Techniques; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000502:physiology; D008970:Molecular Weight; D010247:Paramecium / Q000502:physiology; D010750:Phosphoproteins / Q000502:physiology*
D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010750:Phosphoproteins; D000469:Alkaline Phosphatase