What is a protein?
Proteins are complex organic compounds, consisting of long strings of amino acids, which contain carbon, hydrogen, oxygen, nitrogen and usually sulphur. They are essential constituents of living cells and are found in both plants and animals.
What do proteins do?
There are hundreds upon hundreds of different proteins and together they are involved in blood coagulation (clotting), oxygen transport, muscle contraction, electron transport and other activities throughout the body, including types which serve as enzymes and hormones. Twenty-one different amino acids are commonly found in proteins and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function.
Protein S
Protein S is a Vitamin K-dependent plasma glycoprotein synthesized in the liver and it functions as a cofactor to Protein C in the inactivation of Factors Va and VIIIa. In the circulation, Protein S exists in two forms: a free form and a complex form bound to complement protein C4b. Only the free form has cofactor activity.
http://www.protein.org.uk/protein.php
Last updated: Tuesday, 12th June 2007, © 2000-2008
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