Ba. Jakschik et al., THE EFFECT OF RECEPTOR-MEDIATED STIMULATION ON THE TRANSLOCATION OF 5-LIPOXYGENASE, Agents and actions, 41, 1994, pp. 30000169-30000171
It has been shown that calcium ionophore-mediated activation of the 5-
lipoxygenase is followed by an extensive loss of enzyme activity. We i
nvestigated whether IgE/antigen stimulation of mast cells leads to a s
imilar inactivation. This challenge caused a minor loss of 5-lipoxygen
ase activity as compared to A23187. Both stimuli resulted in the synth
esis of similar amounts of leukotrienes. Immunoblot experiments showed
that after antigen, the membrane association of the enzyme was revers
ible. In contrast, with A23187 translocation continued during the time
of observation (60 min). Calcium chelators, added after A23187 stimul
ation, stopped the enzyme inactivation and reversed the membrane bindi
ng. The data suggest that the continuous, high intracellular calcium l
evels initiated by A23187 inactivate the enzyme, while the transient i
ncrease in calcium during receptor-mediated stimulation is sufficient
to activate the 5-lipoxygenase but not to extensively inactivate it.