question: How many and which are the different isoforms for the ryanodine receptor?
answer: Generally, three ryanodine receptor isoforms (RyR1-RyR3) are known. RyR1, expressed in skeletal muscle; RyR2, expressed in cardiac muscle; and RyR3, expressed in various cells. RyR3 is preferentially expressed in the brain especially in the hippocampus and striatum.