Muscle fibers, in contracting and extending, generate tremendous force that needs to be buffered to protect muscle from damage. This role falls to the protein titin, with about 27,000 amino acids the longest protein in human cells. Titin functions as a molecular rubber band, but unlike uniform rubber bands, titin is made from over 300 different protein domains strung into a chain. While experiments have found that the individual domains of titin feature remarkable resilience against mechanical stretching, little is known about the elasticity of the overall titin chain. Crystallographers teamed up with computational biologists to investigate this elasticity, focusing on two adjacent titin domains. Molecular dynamics simulations using NAMD suggest, as reported recently, that the overall elasticity of the titin chain stems in part from a zigzag, i.e., accordion-like, motion: as titin is contracted and extended, energy is stored and released in the angular tilt of adjacent domains. More on this investigation can be found here.