Sequence features of adiponectin, complement C1q, and the collectins.

The monomer of adiponectin polypeptide (230 amino acids in its mature form) consists of 3 distinct regions: (1) a short N-terminal segment (solid black); (2) a collagen-like, glycine-X-Y repeating sequence (diagonal stripe); and (3) a C-terminal globular domain (hatched pattern). Adiponectin and C1q are similar in size, domain structure, and overall homology. They are different from the collectins in that they have no α-helix (solid white) regions and they contain C-terminal globular domains related to collagen VIII and X rather than the C-type lectin domains (horizontal stripe) in collectins.