Coordinate regulation of RNAs encoding two isoforms of the rat muscle nicotinic acetylcholine receptor beta-subunit.

The nicotinic acetylcholine receptor (nAchR) mediates communication between nerve and skeletal muscle. The properties, levels and distribution of these receptors change during development of the neuromuscular junction. These changes may be due, in part, to expression of different gene products. We are using nuclease protection experiments and cDNA cloning to identify the RNA transcripts that encode nAchRs in rat muscle. This analysis has identified two beta-subunit mRNAs. Complementary DNAs corresponding to these two RNAs have been isolated from a rat skeletal muscle cDNA library. Based on nucleotide sequence analysis, these RNAs differ by 9 bases in their 5' coding sequence. The levels of both mRNAs change similarly during muscle development and upon denervation of adult skeletal muscle. These two beta-subunit-RNAs probably result from the use of different exon/intron splice sites in the beta-subunit gene.