The 'embryonic' gamma subunit of the nicotinic acetylcholine receptor is expressed in adult extraocular muscle

We have PCR-amplified cDNA sequence of the "embryonic" μM subunit of muscle acetylcholine receptor (AChR) from adult bovine extraocular muscle (EOM). We cloned and sequenced this product and used it to probe Northern blots. We detected the μM subunit in EOM mRNA, but not in control skeletal muscle. The presence of y sub-unit in EOMs may explain their preferential involvement in myasthenia gravis, where an autoimmune response to the y subunit is generally present.