The venom of Conus pennaceus inhibits the binding of (3H)neuropeptide Y by direct interaction with the radioligand.

摘要

The venom from the marine snail Conus pennaceus inhibits the binding of [3H]neuropeptide Y to calf brain membranes (Czerwiec et al., 1996a) and, in the present study, also to rat forebrain membranes. These membranes contain about 80% Y1- and 20% Y2-receptors. The inhibition by the venom was concentration-dependent with an IC50 value of 3.4 micrograms ml-1. However, the venom also inhibited the binding of [3H]neuropeptide Y to the glass fibre filters and to the previously discovered ANPY toxin from the venom of Conus anemone (Czerwiec et al., 1996b). This inhibition was related to the ability of one or more of the venom components to bind directly to the radioligand instead of the initially assumed interaction with the neuropeptide Y receptors present in membrane preparations. The complex with Conus pennaceus venom was not retained by the glass fibre filter during the separation of the bound from the unbound [3H]neuropeptide Y. Gel filtration chromatography and denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the active [3H]neuropeptide Y-binding component is likely a approximately 30 kDa polypeptide. Binding of [3H]neuropeptide Y to the venom component(s) was not displaced by 20 microM of the (1-24) N-terminal and the (25-36) C-terminal neuropeptide Y fragments. It is therefore likely that the recognition of the venom component(s) requires both the C- and the N-terminal segments of the neuropeptide Y molecule.