In mammals, C6 interacts with C5b through a metastable binding site to form a soluble C5b:C6 dimer.
Chicken complement component C6 was cloned and characterized [Mikrou A and Zarkadis IK 2010]. It shows 81% of amino acid identity to the predicted sequence of zebra finch C6, followed by human, frog and trout counterparts with 58%, 56%, and 44% identity, respectively. Chicken C6 contains the same structural motifs as those found in mammalian terminal complement components (TSP1, LDLa, MACPF, EGF). In addition, like mammalian C6/C7 components, chicken C6 contains two complement control protein (CCP) motifs. Chicken C6 carries two copies of the FIMAC domain, which has been implicated in the interaction of mammalian C6/C7 proteins with C5.
Chicken C6 mRNA expression was detected in various tissues - liver, brain, heart, kidney [Mikrou A and Zarkadis IK 2010].