RAD21 and atrial fibrillation: Given that Pds5 is intimately involved in RA and that the latter requires dissociation of Scc1’s NTD from Smc3, it is plausible to imagine that upon its dissociation (presumably in response to head engagement and joint junction), Scc1’s NTD remains associated with Pds5 in the conformations observed in the above AF models.