The table and cartoon summarize the head–head, head–tail, and tail–tail interactions in 10S myosin, based on the 3-D reconstruction and fitting. The cartoon corresponds to the reconstruction in Fig. 5 (A and B). Blocked and free heads are represented by red and green, respectively. Yellow dots represent mesa of blocked head. CON, converter; MD, motor domain; SH3, SRC homology 3 domain. TT1 and TT2 mark initial points of contact between segments 1, 2, and 3 and segments 1 and 3, respectively. From these initial points, these segments run closely together and may interact along much of their lengths. Note: Corresponding domains in the two heads have different apparent shapes and sizes in this 2-D representation of the 3-D reconstruction, in which the domains are viewed at different angles (cf. Fig. 5 A).