Kringle domains are autonomous
protein domain
In molecular biology, a protein domain is a region of a protein's Peptide, polypeptide chain that is self-stabilizing and that Protein folding, folds independently from the rest. Each domain forms a compact folded Protein tertiary structure, thre ...
s that fold into large
loops stabilized by three disulfide linkages. These are important in
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
–protein interactions with blood
coagulation
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a thrombus, blood clot. It results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The process of co ...
factors. Their name refers to the
Kringle, a Scandinavian pastry which they somewhat resemble.
Kringle domains have been found in
plasminogen
Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is enco ...
,
hepatocyte
A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass.
These cells are involved in:
* Protein synthesis
* Protein storage
* Transformation of carbohydrates
* Synthesis of cholesterol, bi ...
growth factors,
prothrombin, and
apolipoprotein(a).
Kringles are found throughout the
blood clotting
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a thrombus, blood clot. It results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The process of co ...
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.
Kringle domains
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.
Human proteins containing this domain
ATF;
F12;
F2;
HABP2;
HGF;
HGFAC;
KREMEN1;
KREMEN2;
LPA;
LPAL2;
MST1;
PIK3IP1;
PLAT
In the United States, a plat ( or ) (plan) is a cadastral map, drawn to scale, showing the divisions of a piece of land. United States General Land Office surveyors drafted township plats of Public Lands Survey System, Public Lands Surveys to ...
;
PLAU;
PLG;
PRSS12;
ROR1;
ROR2
Tyrosine-protein kinase transmembrane receptor ROR2, also known as neurotrophic tyrosine kinase, receptor-related 2, is a protein that in humans is encoded by the ''ROR2'' gene located on position 9 of the long arm of chromosome 9 (human), chrom ...
;
References
External links
Kringle domain in
PROSITE
KR domain entry in the SMART database
{{Protein domains
Protein domains
Peripheral membrane proteins