Referenced in: none

Automatically associated channels: Kv2.1

Title: Sucrase-isomaltase is an adenosine 3',5'-cyclic monophosphate-dependent epithelial chloride channel.

Authors: A L Finn, E V Kuzhikandathil, G S Oxford, Y Itoh-Lindstrom

Journal, date & volume: Gastroenterology, 2001 Jan , 120, 117-25

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11208720

Abstract
We previously isolated a monoclonal antibody against a Necturus gallbladder epitope that blocks native adenosine 3',5'-cyclic monophosphate (cAMP)-dependent chloride channels in intestine, gallbladder, urinary bladder, and airway epithelia in various animals.Using this antibody, we purified a 200-kilodalton protein that, when reconstituted in lipid bilayers, forms 9-pS chloride channels that are blocked by the antibody.Amino acid sequencing of the purified protein showed strong homology to rabbit sucrase-isomaltase, an abundant intestinal enzyme. Western blot analysis of the in vitro-translated sucrase-isomaltase was indistinguishable from that of the protein used in the lipid bilayer studies. Expression of this protein in Chinese hamster ovary cells and in Xenopus laevis oocytes yielded cAMP-dependent chloride currents that in the latter system were blocked by the antibody.Because the monoclonal antibody blocks cAMP-dependent currents in epithelia as well as those produced both by the reconstituted and by the heterologously expressed protein, sucrase-isomaltase is a cAMP-dependent epithelial chloride channel. Thus an enzyme that can also function as an ion channel has been described for the first time.