End-block association dynamics are known to influence deformation behavior in block copolymer systems. A The ability to obtain precisely sequence controlled systems can 3 0 help inform this deformation behavior, which is often influenced by dispersity in sequence and molar mass. Elastinlike polypeptides (ELPs) are a class of protein that consists of a sequence of five amino acids (XPGVG) that thermoresponsively aggregate in solution. These ELPs can be used as end-blocks in triblock fusion proteins with coiled-coil associating midblock domains to result in dual-associating, network-forming materials. By modifying the standard glycine- 20 degrees C containing ELP sequence (XPGVG) to instead contain alanine in the third position of the repeat sequence (XPAVG), it is possible to improve the properties of the material in both shear and extension. In extension at 50 degrees C, the alanine-containing triblock (A(10)P(4)A(10)) and the glycine-containing triblock (G(10)P(4)G(10)) have similar Young's moduli. However, while G(10)P(4)G(10) yields and breaks within 5 strain units, A(10)P(4)A(10) plastically deforms to an ultimate strain at break of over 15 strain units and a tensile stress of almost 90 kPa. In shear, G(10)P(4)G(10) exhibits a clear stress overshoot at less than one strain unit before plateauing at a steady-state shear stress of 0.43 kPa, while the shear stress of A10P4A70 monotonically increases to a shear stress of 48.4 kPa after 2.4 strain units. In shear, these differences in behavior correlate to rearrangement of G10P4Gio's nanostructure during viscous dominated flow, while the nanostructure of A(10)P(4)A(10) initially elastically deforms. These differences are a function of the relative network relaxation time scales, where the presence of the faster glycine-containing ELP end-block sequence decreases the network relaxation time such that it occurs on the same order of magnitude as the imposed flow.