Alternative splicing generates multiple mRNA forms of the acetylcholine receptor gamma-subunit in rat muscle

The fetal type acetylcholine receptor, composed of the alpha beta gamma del ta subunits, has shown a highly variable channel kinetics during postnatal development. We examine the hypothesis whether such a variability could res ult from multiple channel forms, differing in the N-terminus of the gamma-s ubunit. RT-PCR revealed, in addition to the full-length mRNA, three new for ms lacking exon 4, One of them in addition lacks 19 nucleotides from exon 5 , predicting a complete subunit, with a 43 residues shorter N-terminus. A t hird one lacking the complete exon 5 predicts a subunit without transmembra ne segments. These forms, generated by alternative splicing, may account fo r the kinetic variability of the acetylcholine receptor channel. (C) 1999 F ederation of European Biochemical Societies.