<prompt> The anti- acetylcholine receptor AChR antibodies in myasthenia gravis reduce the number of available AChRs at neuromuscular junctions with which of the following mechanism?accelerated turnover of AChRsdamage to the postsynaptic muscle membraneblockade of the active site of the AChRall of the above  <response>: The anti-AChR antibodies reduce the number of available AChRs at NMJs by three distinct mechanisms: 1 accelerated turnover of AChRs by a mechanism involving cross-linking and rapid endocytosis of the receptors; 2 damage to the postsynaptic muscle membrane by the antibody in collaboration with complement; and 3 blockade of the active site of the AChR. Ref harrison 20th edition page 3232 