Protein S is a
vitamin K-dependent plasma
glycoprotein synthesized in the liver. In the circulation,
Protein S exists in two forms: a free form and a complex form
bound to
complement protein C4b.
Function
The best characterized function of Protein S is its role in
the anti
coagulation pathway, it functions as a cofactor to
Protein C in the inactivation of
Factors Va and
VIIIa. Only the free form has cofactor activity.
Protein S can bind to negatively charged
phospholipids via the carboxylated GLA domain. This property
allows Protein S to function in the removal of cells which are
undergoing
apoptosis.
Apoptosis is a form of cell death that is used by the body
to remove unwanted or damaged cells from tissues. Cells which
are apoptotic (ie. in the process of
apoptosis) no longer actively manage the distribution of
phospholipids in their outer membrane and hence begin to display
negatively charged phospholipids, such as phosphatidyl serine,
on the cell surface. In healthy cells, an ATP (Adenosine
triphosphate)-dependent enzyme removes these from the outer
leaflet of the cell membrane. These negatively charged
phospholipids are recognized by
phagocytes such as
macrophages. Protein S can bind to the negatively charged
phospholipids and function as a bridging molecule between the
apoptotic cell and the phagocyte. The bridging property of
Protein S enhances the phagocytosis of the apoptotic cell,
allowing it to be removed 'cleanly' without any symptoms of
tissue damage such as
inflammation occurring.
Pathology
Protein S deficiency is a rare blood disorder which can lead
to an increased risk of
thrombosis.
See also
Further reading
-
Dahlbäck B (1991). "Protein S and C4b-binding protein:
components involved in the regulation of the protein C
anticoagulant system". Thromb. Haemost. 66
(1): 49–61.
PMID 1833851.
-
Witt I (2002). "[Molecular biological basis and
diagnosis of hereditary defect of antithrombin III,
protein c and protein S]". Hamostaseologie 22
(2): 14–24.
doi:10.1267/Hamo02020057 (inactive 22 June 2008).
PMID 12193972.
-
Rezende SM, Simmonds RE, Lane DA (2004). "Coagulation,
inflammation, and apoptosis: different roles for protein
S and the protein S-C4b binding protein complex".
Blood 103 (4): 1192–201.
doi:10.1182/blood-2003-05-1551.
PMID 12907438.
-
Dahlbäck B (2007). "The tale of protein S and
C4b-binding protein, a story of affection". Thromb.
Haemost. 98 (1): 90–6.
PMID 17597997.
-
García de Frutos P, Fuentes-Prior P, Hurtado B, Sala N
(2007). "Molecular basis of protein S deficiency".
Thromb. Haemost. 98 (3): 543–56.
PMID 17849042.
-
Maillard C, Berruyer M, Serre CM, et al. (1992).
"Protein-S, a vitamin K-dependent protein, is a bone
matrix component synthesized and secreted by
osteoblasts". Endocrinology 130 (3):
1599–604.
doi:10.1210/en.130.3.1599.
PMID 1531628.
-
Griffin JH, Gruber A, Fernández JA (1992). "Reevaluation
of total, free, and bound protein S and C4b-binding
protein levels in plasma anticoagulated with citrate or
hirudin". Blood 79 (12): 3203–11.
PMID 1534488.
-
Guglielmone HA, Vides MA (1992). "A novel functional
assay of protein C in human plasma and its comparison
with amidolytic and anticoagulant assays". Thromb.
Haemost. 67 (1): 46–9.
PMID 1615482.
-
Bertina RM, Ploos van Amstel HK, van Wijngaarden A,
et al. (1990). "Heerlen polymorphism of protein S,
an immunologic polymorphism due to dimorphism of residue
460". Blood 76 (3): 538–48.
PMID 2143091.
-
Schmidel DK, Tatro AV, Phelps LG, et al. (1991).
"Organization of the human protein S genes".
Biochemistry 29 (34): 7845–52.
doi:10.1021/bi00486a010.
PMID 2148110.
-
Ploos van Amstel HK, Reitsma PH, van der Logt CP,
Bertina RM (1991). "Intron-exon organization of the
active human protein S gene PS alpha and its pseudogene
PS beta: duplication and silencing during primate
evolution". Biochemistry 29 (34): 7853–61.
doi:10.1021/bi00486a011.
PMID 2148111.
-
Allaart CF, Aronson DC, Ruys T, et al. (1991).
"Hereditary protein S deficiency in young adults with
arterial occlusive disease". Thromb. Haemost.
64 (2): 206–10.
PMID 2148653.
-
Ohlin AK, Landes G, Bourdon P, et al. (1989).
"Beta-hydroxyaspartic acid in the first epidermal growth
factor-like domain of protein C. Its role in Ca2+
binding and biological activity". J. Biol. Chem.
263 (35): 19240–8.
PMID 2461936.
-
Schwarz HP, Heeb MJ, Lottenberg R, et al. (1989).
"Familial protein S deficiency with a variant protein S
molecule in plasma and platelets". Blood 74
(1): 213–21.
PMID 2526663.
-
Ploos van Amstel HK, van der Zanden AL, Reitsma PH,
Bertina RM (1987). "Human protein S cDNA encodes Phe-16
and Tyr 222 in consensus sequences for the
post-translational processing". FEBS Lett. 222
(1): 186–90.
doi:10.1016/0014-5793(87)80217-X.
PMID 2820795.
-
Dahlbäck B, Lundwall A, Stenflo J (1986). "Primary
structure of bovine vitamin K-dependent protein S".
Proc. Natl. Acad. Sci. U.S.A. 83 (12):
4199–203.
doi:10.1073/pnas.83.12.4199.
PMID 2940598.
-
Lundwall A, Dackowski W, Cohen E, et al. (1986).
"Isolation and sequence of the cDNA for human protein S,
a regulator of blood coagulation". Proc. Natl. Acad.
Sci. U.S.A. 83 (18): 6716–20.
doi:10.1073/pnas.83.18.6716.
PMID 2944113.
-
Engesser L, Broekmans AW, Briët E, et al. (1987).
"Hereditary protein S deficiency: clinical
manifestations". Ann. Intern. Med. 106
(5): 677–82.
PMID 2952034.
-
Watkins PC, Eddy R, Fukushima Y, et al. (1988).
"The gene for protein S maps near the centromere of
human chromosome 3". Blood 71 (1): 238–41.
PMID 2961379.