Structure and function of fibrinogen BβN-domains

Two BβN-domains of fibrinogen are formed by the N-terminal portions of its two Bβ chains including amino acid residues Bβ1-65. Although their folding status is not well understood and the recombinant disulfide-linked (Bβ1-66)₂ fragment corresponding to a pair of these domains was found to be unfolded, some data suggest that these domains may be folded in the parent molecule. In contrast, their major functional properties are well established. Removal of fibrinopeptides B (amino acid residues Bβ1-14) from these domains upon fibrinogen to fibrin conversion results in the exposure of multiple binding sites in fibrin βN-domains (residues β15-65). These sites provide interactions of the βN-domains with different proteins and cells and their participation in various physiological and pathological processes including fibrin assembly, fibrin-dependent angiogenesis, and fibrin-dependent leukocyte transmigration and thereby inflammation. The major goal of the present review is to summarize current view on the structure and function of these domains in fibrinogen and fibrin and their role in the above-mentioned processes.