Plasma protein

 ( Blood Proteins ) 

Plasma proteins, sometimes referred to as blood proteins, are present in blood plasma. They perform many different functions, including transport of , and in activity and functioning of the immune system. Other blood proteins act as , complement, components, protease inhibitors or . Contrary to popular belief, haemoglobin is not a blood protein, as it is carried within red blood cells, rather than in the blood serum.

Serum albumin accounts for 55% of blood proteins, is a major contributor to maintaining the oncotic pressure of plasma and assists, as a carrier, in the transport of lipids and . make up 38% of blood proteins and transport , hormones, and lipids assisting in immune function. Fibrinogen comprises 7% of blood proteins; conversion of fibrinogen to insoluble fibrin is essential for blood clotting. The remainder of the plasma proteins (1%) are regulatory proteins, such as enzymes, , and hormones. All blood proteins are synthesized in liver except for the .

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Families of blood proteins

Examples of specific blood proteins:

• Prealbumin (transthyretin)
• Alpha 1 antitrypsin (neutralizes trypsin that has leaked from the digestive system)
• Alpha-1-acid glycoprotein
• Alpha-1-fetoprotein
• alpha2-macroglobulin
• Beta-2 microglobulin
• Haptoglobin
• Human Serum Albumin
• Ceruloplasmin
• Complement component 3
• Complement component 4
• C-reactive protein (CRP)
• (chylomicrons, VLDL, LDL, HDL)
• Transferrin
• Prothrombin
• MBL or MBP

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Clinical significance Separating blood serum proteins by electrophoresis is a valuable Diagnosis, as well as a way to monitor Healing. Current research regarding blood plasma proteins is centered on performing proteomics analyses of serum/plasma in the search for . These efforts started with two-dimensional gel electrophoresis efforts in the 1970s, and in more recent times this research has been performed using LC-tandem MS based proteomics. The normal laboratory value of serum total protein is around 7 g/dL.

Scientists are able to identify blood proteins using Photo-affinity labeling, a means of using photo-reactive ligands as a labeling agent to identify targeted proteins.

• Clinical Chemistry : a laboratory perspective / edited Wendy Arneson, Jean Brickell.

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