Editing Plasma protein (section)

{{Short description|Proteins present in blood serum}}

'''Plasma proteins''', sometimes referred to as '''blood proteins''', are [[protein]]s present in [[blood plasma]]. They perform many different functions, including transport of [[hormone]]s, [[vitamin]]s and [[mineral]]s in activity and functioning of the [[immune system]]. Other blood proteins act as [[enzyme]]s, complement, components, [[protease inhibitors]] or [[kinin precursor]]s. Contrary to popular belief, [[haemoglobin]] is not a blood protein, as it is carried within [[red blood cell]]s, rather than in the blood [[serum (blood)|serum]].

[[Serum albumin]] accounts for 55% of blood proteins,<ref name=":0">{{Citation|last1=Smith|first1=Graham S.|title=Chapter 18 - Clinical Pathology in Non-Clinical Toxicology Testing|date=2013-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780124157590000182|work=Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition)|pages=565–594|editor-last=Haschek|editor-first=Wanda M.|place=Boston|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-415759-0.00018-2|isbn=978-0-12-415759-0|access-date=2020-11-16|last2=Walter|first2=Gail L.|last3=Walker|first3=Robin M.|editor2-last=Rousseaux|editor2-first=Colin G.|editor3-last=Wallig|editor3-first=Matthew A.|url-access=subscription}}</ref> is a major contributor to maintaining the [[oncotic pressure]] of plasma and assists, as a carrier, in the transport of lipids and [[steroid hormone]]s.  [[Globulin]]s make up 38% of blood proteins and transport [[ion]]s, 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 protein]]s, such as enzymes, [[proenzyme]]s, and [[hormones]]. All blood proteins are synthesized in [[liver]] except for the [[gamma globulin]]s.<ref name=":0" />