... inhibitsallosterically the b inding of the s corpion a-tox in, Aah-II, to rat brain synaptosomes [27,28]. To examine the similarity inbinding to receptor site-3 between scorpion a-toxins and d-ACTXs, we analysed ... of PbTx-1 on125I-labelledd-ACTX-Hv1a binding to rat brain synaptosomes. Simi-larly to the effect of PbTx-1 on Aah-II binding [27,28],this brevetoxin substantially inhibited the binding of 125I-labelled ... position, and interestingly, a lso appear on th esurface of d-ACTX-Hv1a (Fig. 6). The positively chargedLys3, Lys4, Arg5, and Lys10 of d-ACTX-Hv1a are orientedsimilarly to Lys8, Arg58, Lys62, and...