Fragment of bovine
prothrombin in complex with calcium and
lysophosphatidylserine. The protein associate with membrane through its alpha-helical
GLA domain. The adjacent kringle domain is beta-structural (yellow).
Kringle domains are autonomous
protein domains that fold into large
loops stabilized by 3 disulfide linkages. These are important in
protein–protein interactions with blood
coagulation factors. Their name refers to the
Kringle, a Scandinavian pastry which they somewhat resemble.
Kringles are found throughout the
blood clotting and fibrinolytic proteins. Kringle domains are believed to play a role in binding mediators (e.g., membranes, other proteins or phospholipids), and in the regulation of proteolytic activity.[1][2][3] Kringle domains[4][5][6] are characterised by a triple loop, 3-disulfide bridge structure, whose conformation is defined by a number of hydrogen bonds and small pieces of anti-parallel beta-sheet. They are found in a varying number of copies in some plasma proteins including prothrombin and urokinase-type plasminogen
activator, which are serine proteases belonging to MEROPS peptidase family S1A.
^Atkinson RA, Williams RJ (1990). "Solution structure of the kringle 4 domain from human plasminogen by 1H nuclear magnetic resonance spectroscopy and distance geometry". J. Mol. Biol. 212 (3): 541–552.
doi:
10.1016/0022-2836(90)90330-O.
PMID2157850.
^Castellino FJ, Beals JM (1987). "The genetic relationships between the kringle domains of human plasminogen, prothrombin, tissue plasminogen activator, urokinase, and coagulation factor XII". J. Mol. Evol. 26 (4): 358–369.
Bibcode:
1987JMolE..26..358C.
doi:
10.1007/BF02101155.
PMID3131537.
S2CID22249781.