... determination and cloning of the cDNAencoding two novel peptides, SrIA and SrIB, found in the venom of Conus spurius. The pattern and the spa-cing of their cysteines indicate that they belong to the a4 ... aA families.On the basis of the number of residues between the sec-ond and third cysteines and on the spacing between the third and fourth cysteines in the mature a-conotoxins, these peptides ... C. spurius a-conotoxins, and of a synthetic analog of one of them, on three of the more important types of acetylcholine receptor.Moreover, while comparing these properties with those of the...