TRUNCATED FORM OF PRO-ACETYLCHOLINE RECEPTOR-INDUCING ACTIVITY (ARIA)INDUCES ACHR ALPHA-SUBUNIT BUT NOT ACHE TRANSCRIPTS IN CULTURED CHICKMYOTUBES

Acetylcholine receptor-inducing activity (ARIA) is a glycoprotein init ially purified from chick brain based on its ability to increase the s ynthesis of acetylcholine receptor (AChR). We used reverse transcripti on-polymerase chain reaction (RT-PCR) to obtain a partial pro-ARIA cDN A clone from methonine-1 to serine-358 including the full functional s equence of ARIA. Northern blot analysis of mRNAs from the embryonic ch ick brain and muscle showed a transcript with a size of similar to 7.5 kb. The cloned cDNA was subcloned into an eukaryotic expression vecto r and stably transfected into human embryonic kidney 293 cells. The co nditioned medium of the transfected cells was found to increase the le vel of transcript encoding for the alpha-subunit of AChR by similar to 4.4-fold, but not for acetylcholinesterase (AChE), in the cultured ch ick myotubes.