Proteins are essential building blocks of biogenic materials. In addition to purely protein-based materials, a wide range of different composite materials are formed in Nature, where proteins mediate specific interactions with other biopolymers (e.g., polysaccharides) or mineral surfaces (e.g., magnetite). Using single-molecule force spectroscopy, our key goal is to establish the fundamental sequence-structure-MECHANICS relationships of such interactions to subsequently utilize these for the bottom-up assembly of mechanoresponsive bioinspired materials. In this talk, two examples of protein building blocks will be highlighted. The first example introduces coiled coils, which are highly abundant building blocks in mammalian tissues. Using a library of mechanically characterized coiled coils as hydrogel crosslinks, the viscoelastic properties of the obtained hydrogels can be controlled both at the level of individual coiled coils and via their self-assembly into higher-order structures. The second example shows magnetite-binding proteins, derived from magnetotactic bacteria. Even though these proteins do not experience force in Nature, engineered variants with controlled binding strength can potentially serve as powerful building blocks for controlling the viscoelastic properties of magnetic particle-reinforced composites.