Tropoelastin is a protein that serves as the building block for elastin, a key component of connective tissues in the body. It is produced by cells called fibroblasts and plays a crucial role in providing elasticity and resilience to tissues such as skin, lungs, and blood vessels. When tropoelastin molecules are secreted into the extracellular matrix, they undergo a process called cross-linking, which forms elastin fibers. These fibers allow tissues to stretch and return to their original shape, contributing to the overall flexibility and durability of various organs and structures in the body.