Blood proteins

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Blood proteins, also termed plasma proteins or serum proteins, are proteins present in blood plasma. They serve many different functions, including transport of lipids, hormones, vitamins and minerals in the circulatory system and the regulation of acellular activity and functioning of the immune system. Other blood proteins act as enzymes, complement components, protease inhibitors or kinin precursors. Contrary to popular belief, hemoglobin 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, and is a major contributor to maintaining the osmotic pressure of plasma to assist in the transport of lipids and steroid hormones. Globulins make up 38% of blood proteins and transport ions, 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, proenzymes, and hormones. All blood proteins are synthesized in liver except for the gamma globulins.

Separating serum proteins by electrophoresis is a valuable diagnostic tool as well as a way to monitor clinical progress. Current research regarding blood plasma proteins is centered on performing proteomics analyses of serum/plasma in the search for biomarkers. These efforts started with two-dimensional gel electrophoresis[1] efforts in the 1970s and in more recent times this research has been performed using LC-tandem MS[2][3][4] based proteomics. The normal laboratory value of serum total protein is around 7 g/dL.

Families of blood proteins[edit]

Blood protein Normal level  % Function
Albumins 3.5-5.0 g/dl[citation needed] 55% create and maintain oncotic pressure; transport insoluble molecules
Globulins 2.0-2.5 g/dl[citation needed] 38% participate in immune system
Fibrinogen 0.2-0.45 g/dl[citation needed] 7% Blood coagulation
Regulatory proteins <1%[citation needed] Regulation of gene expression
Clotting factors <1%[citation needed] Conversion of fibrinogen into fibrin

Examples of specific blood proteins:


  1. ^ Anderson NL, Anderson NG (1977). "High Resolution Two-Dimensional Electrophoresis of Human Plasma Proteins". Proceedings of the National Academy of Sciences. 74 (12): 5421–5425. PMC 431746Freely accessible. PMID 271964. doi:10.1073/pnas.74.12.5421. 
  2. ^ Adkins JN; et al. (2002). "Toward a human blood serum proteome: analysis by multidimensional separation coupled with mass spectrometry". Molecular & Cellular Proteomics. 1 (12): 947–955. PMID 12543931. doi:10.1074/mcp.M200066-MCP200. 
  3. ^ Malmström, E; Kilsgård, O; Hauri, S; Smeds, E; Herwald, H; Malmström, L; Malmström, J (January 2016). "Large-scale inference of protein tissue origin in gram-positive sepsis plasma using quantitative targeted proteomics". Nat Commun. 7. PMID 26732734. doi:10.1038/ncomms10261. 
  4. ^ Geyer, PE; Kulak, NA; Pichler, G; Holdt, LM; Teupser, D; Mann, M (March 2016). "Plasma Proteome Profiling to Assess Human Health and Disease". Cell Syst. 2 (3): 185–95. PMID 27135364. doi:10.1016/j.cels.2016.02.015. 


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