Hopkins Marine Station Student Paper

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Title: Conus striatus venom exhibits no significant effects on potassium currents in a Xenopus oocyte expression system
Student Author(s): Hughes, Michael
Faculty Advisor(s): Gilly, william
Pages: 16
Location: Final Papers Biology 176H
Date: June 2001
Abstract: Conus striatus is a predatory cone snail that subdues its prey with a wide array of neuroactive peptides. The milked venom of striatus has been shown to induce paralytic seizures when injected into fish and repetitive action potentials in frog sympathetic ganglion cells and neuromuscular junction (Joseph Schulz, personal communication). Recently, Craig et al. (1998) reported that the primary peptide constituent of the milked venom of C. striatus is a 4kD o-glycosylated peptide, named kA-conotoxin SIVA, and proposed that this peptide acts as a low affinity antagonist of Shaker potassium channels. In order to identify a specific, high affinity target of kA-conotoxin, experiments were carried out with Xenopus oocytes injected with mRNA encoding various voltage gated potassium channels. The pharmacological effects of milked venom on these channels were assayed using a conventional, two electrode voltage clamp method. None of the potassium channels tested (Xenopus Kv1.1, 1.2, 1.3 and Shaker B 6-46, 6-46 T449V) were significantly affected by milked venom at concentrations well above the minimum amount required to induce repetitive firing of frog neuromuscular junction. These data indicate that the high affinity target of kA-conotoxin is not one of the Shaker homologues tested.