Final answer:
MBL and ficolin's possess a collagen-like trimer structure, which is essential for their role in the innate immune system and pathogen recognition.
Step-by-step explanation:
The structure of mannose-binding lectin (MBL) and ficolins resembles a collagen-like trimer. Both MBL and ficolins are part of the innate immune system and play a crucial role in pathogen recognition. These proteins are characterized by having a collagen-like domain that allows them to form trimeric structures. This arrangement is crucial for their functional ability to bind to the surface of pathogens and initiate an immune response through the lectin pathway of complement activation. The collagen-like structure helps in the formation of a lattice that is necessary for the high-avidity binding to target surfaces.