β-cardiac myosin motility surface attachment strategy. The use of an anti-GFP nanobody to attach myosin constructs to the motility surface improves velocity of the S1 and 2HEP WT constructs, which are incapable of adopting the IHM/SRX state, by at least a factor of 2. This result suggests that the nanobody attachment strategy allows myosin heads to interact properly with actin without surface interference. Data represent mean values ± SD from three independent protein preparations.