Explain the vitamin k dependent proteins, Biology

Assignment Help:

Explain the Vitamin K dependent proteins?

The four vitamin K-dependent procoagulants (factor II or prothrombin, and factors VII, IX, and X), about which we studied above, are serine proteases that are synthesized in the liver and then secreted into the circulation as inactive forms (zymogens). Their biological activity depends on their normal complement of Gla residues, which are efficient chelators of calcium ions. In the presence of Gla residues and calcium ions, these proteins bind to the surface membrane phospholipids of platelets and endothelial cells where, together with other cofactors, they form membrane-bound enzyme complexes. When coagulation is initiated, the zymogens of the four vitamin K-dependent clotting factors are cleaved to yield the active protease clotting factors.

Two other vitamin K-dependent proteins, protein C and protein S, play a regulatory role in the inhibition of coagulation. The function of protein C is to degrade phospholipid- bound activated factors V and VIII in the presence of calcium. Protein S acts as a synergistic cofactor to protein C by enhancing the binding of activated protein C to negatively charged phospholipids. There is evidence that protein S is synthesized by several tissues including the blood vessel wall and bone and may have other functions besides its well-established role as a coagulation inhibitor. Yet another vitamin K-dependent plasma protein (protein 2) is suspected to have a haemostatic role but its function is currently unknown.

Apart from the coagulation proteins, several other vitamin K-dependent proteins have been isolated from bone, cartilage, kidney, lungs and other tissues. Only two, osteocalcin and nlatrix Gla protein (MGP), have been well characterized. Both are found in bone but MGP also occurs in cartilage, blood vessel walls, and other soft tissues. One function of MGP is to inhibit mineralization. Thus far, no clear biological role for osteocalcin has been established despite its being the major noncollagenous bone protein synthesized by osteoblasts. Nephrocalcin has been isolated from kidney and urine. Atherocalcin, plaque Gla protein proline rich Gla proteins have been identified from atheromatous plaques, spinal and thyroid tissues.


Related Discussions:- Explain the vitamin k dependent proteins

Explain pound cake test - preformance evaluation, Pound cake test In so...

Pound cake test In some cases, oil or margarine creaming volume is most accuratelymeasured by preparing a regular pound cake, omitting the chemical leavener andmeasuring the vo

Explain about the biofertilizers, Explain about the Biofertilizers Biof...

Explain about the Biofertilizers Biofertilizers, are the cultures of microorganisms used for inoculating seed or soil or both under ideal conditions to increase the availabilit

Gifted species - biological nitrogen-fixation, Gifted Species - Biological ...

Gifted Species - Biological Nitrogen-Fixation Biological nitrogen fixation remains mainly confined to a few distinct nutritional types of prokaryotes, some of which are free-l

What is the natural habitat of e.coli, What is the natural habitat of E.col...

What is the natural habitat of E.coli? The E.coli was first recognized in the colon region of large intestine and so it was given the name "coli" (found in colon) they are coli

Explain anaplerotic reactions, Anaplerotic Reactions Anaplerotic  reac...

Anaplerotic Reactions Anaplerotic  reactions are  reactions  that  replenish the  intermediates of  citric acid cycle. The  special  enzymatic mechanisms  by  which  the  pool

Explain about the adolescent pregnancy, Explain about the Adolescent Pregna...

Explain about the Adolescent Pregnancy? The pregnant adolescent is viewed as a high-risk patient, highly susceptible to suboptimal pregnancy outcome. Even when not pregnant, a

Contraceptive pill - reproduction, Contraceptive Pill - Reproduction ...

Contraceptive Pill - Reproduction About sixty million women in the world are currently using oral steroid contraceptives. These contraceptives usually consist of a synthetic

The population thus contains secretors, The A and B antigens in humans may ...

The A and B antigens in humans may be found in water-soluble form in secretions, including saliva, of some individuals (Se/Se and Se/se) but not in others (se/se). The population t

Haemocyanin - respiratory pigments, Haemocyanin - Respiratory Pigments ...

Haemocyanin - Respiratory Pigments This pigment is found in several arthropods and molluscs. Haemocyanins do not consist of haee groups. The metal they consist of is copper, w

Treatment of acute myocardial infarction, Q. Streptokinase is a substance u...

Q. Streptokinase is a substance used in the treatment of acute myocardial infarction. How does this substance act? Substances known as fibrinolytics, like urokinase and strepto

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd