the 380 kDa motor unit of dynein belongs to the AAA class of chaperone-like ATPases. The core of the 380 kDa motor unit contains a concatenated chain of six AAA modules, of which four correspond to the ATP binding sites with P-loop signatures described previously, and two are modules in which the P loop has been lost in evolution. This family is the region between D4 and D5 and is the two predicted alpha-helical coiled coil segments that form the stalk supporting the ATP-sensitive microtubule binding component [1].

1: Model for the motor component of dynein heavy chain based on homology to the AAA family of oligomeric ATPases. Mocz G, Gibbons IR; Structure. 2001;9:93-103. PMID:11250194