Identification of an alternatively processed nicotinic receptor alpha7 subunit RNA in mouse brain.

The data in this report describe the discovery and characterization of a previously unidentified alternatively processed RNA for the neuronal nicotinic receptor alpha7 subunit. The unique transcript contains an extra exon that arises from alternative splicing of intron nine of the alpha7 subunit RNA. The alpha7 subunit protein resulting from this alternatively processed RNA is truncated shortly after transmembrane domain three. The variant protein also has a predicted amino acid substitution in the large N-terminal domain as a consequence of a non-templated nucleotide substitution present in the variant alpha7 subunit RNA. The mechanism responsible for the nucleotide substitution is not known. Initial characterization of the variant alpha7 subunit suggests that it is expressed in mouse brain in a pattern similar to the standard alpha7 subunit although at reduced levels. The variant alpha7 subunit was also found to act as a dominant-negative effecter of normal alpha7 subunit function.