Cid, L. Pablo, María-Isabel Niemeyer, Alfredo Ramírez, and Francisco V. Sepú lveda. Splice variants of a ClC-2 chloride channel with differing functional characteristics. Am J Physiol Cell Physiol 279: C1198-C1210, 2000.-We identified two ClC-2 clones in a guinea pig intestinal epithelial cDNA library, one of which carries a 30-bp deletion in the NH 2 terminus. PCR using primers encompassing the deletion gave two products that furthermore were amplified with specific primers confirming their

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... henticity. The corresponding genomic DNA sequence gave a structure of three exons and two introns. An internal donor site occurring within one of the exons accounts for the deletion, consistent with alternative splicing. Expression of the variants gpClC-2 and gpClC-2⌬77-86 in HEK-293 cells generated inwardly rectifying chloride currents with similar activation characteristics. Deactivation, however, occurred with faster kinetics in gpClC-2⌬77-86. Site-directed mutagenesis suggests that a protein kinase C-mediated phosphorylation consensus site lost in gpClC-2⌬77-86 is not responsible for the observed change. The deletion-carrying variant is found in most tissues examined, and it appears more abundant in proximal colon, kidney, and testis. The presence of a splice variant of ClC-2 modified in its NH 2terminal domain could have functional consequences in tissues where their relative expression levels are different. chloride secretion; alternative splicing; guinea pig; channel deactivation; intestinal epithelium