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{{About|the family of mammalian albumin proteins|the human variant|human serum albumin|the cow variant|bovine serum albumin|the chicken variant|conalbumin}}
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'''Serum albumin''', often referred to simply as '''blood albumin''', is an [[albumin]] (a type of globular [[protein]]) found in vertebrate [[blood]]. [[Human serum albumin]] is encoded by the ''ALB'' [[gene]].<ref name="pmid6292049">{{cite journal | vauthors = Hawkins JW, Dugaiczyk A | title = The human serum albumin gene: structure of a unique locus | journal = Gene | volume = 19 | issue = 1 | pages = 55–8 | year = 1982 | pmid = 6292049 | doi = 10.1016/0378-1119(82)90188-3 }}</ref><ref name="pmid6192711">{{cite journal | vauthors = Harper ME, Dugaiczyk A | title = Linkage of the evolutionarily-related serum albumin and alpha-fetoprotein genes within q11-22 of human chromosome 4 | journal = American Journal of Human Genetics | volume = 35 | issue = 4 | pages = 565–72 | date = July 1983 | pmid = 6192711 | pmc = 1685723 | doi =  }}</ref><ref name="entrez">{{cite web | title = Entrez Gene: albumin| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=213| accessdate = }}</ref> Other [[mammal]]ian forms, such as [[bovine serum albumin]], are chemically similar.


==Overview==
Serum albumin is produced by the [[liver]], occurs dissolved in [[blood plasma]] and is the most abundant [[blood protein]] in [[mammal]]s. Albumin is essential for maintaining the [[oncotic pressure]] needed for proper distribution of [[body fluid]]s between blood vessels and body tissues; without albumin, the high pressure in the blood vessels would force more fluids out into the tissues. It also acts as a plasma carrier by non-specifically binding several [[hydrophobic]] [[steroid hormones]] and as a transport protein for [[hemin]] and [[fatty acid]]s. Too much or too little circulating serum albumin may be harmful. Albumin in the urine usually denotes the presence of kidney disease. Occasionally albumin appears in the urine of normal persons following long standing ([[postural albuminuria]]).
[[Serum albumin]], often referred to simply as '''albumin''', is the most abundant [[plasma protein]] in humans and other [[mammal]]s. Albumin is essential for maintaining the [[osmotic pressure]] needed for proper distribution of [[body fluid]]s between intravascular compartments and body tissues. It also acts as a plasma carrier by non-specifically binding several [[hydrophobic]] [[steroid hormones]] and as a transport protein for [[hemin]] and [[fatty acid]]s.


==Types==
== Function ==
Albumin functions primarily as a carrier protein for [[steroid]]s, [[fatty acid]]s, and [[thyroid hormone]]s in the blood and plays a major role in stabilizing extracellular fluid volume by contributing to [[oncotic pressure]] (known also as colloid osmotic pressure) of plasma.


* The human version is [[human serum albumin]].  
Because smaller animals (for example [[rat]]s) function at a lower [[blood pressure]], they need less oncotic pressure to balance this{{Citation needed|date=May 2016}}, and thus need less albumin to maintain proper fluid distribution.
* [[Bovine serum albumin]], or BSA, is commonly used in immunodiagnostic procedures, clinical chemistry reagents, cell culture media, protein chemistry research and [[molecular biology]] laboratories.
 
==Synthesis==
Albumin is synthesized in the [[liver]] as preproalbumin which has an [[N-terminus|N-terminal]] peptide that is removed before the nascent protein is released from the rough [[endoplasmic reticulum]]. The product, proalbumin, is in turn cleaved in the [[Golgi apparatus|Golgi vesicle]]s to produce the secreted albumin.<ref name="entrez"/>
 
== Properties ==
Albumin is a globular, water-soluble, un-[[glycosylation|glycosylated]] serum protein of approximate molecular weight of 65,000 [[Unified_atomic_mass_unit|Daltons]].
 
Albumin (when ionized in water at pH 7.4, as found in the body) is negatively charged. The [[glomerular basement membrane]] is also negatively charged in the body; some studies suggest that this prevents the filtration of albumin in the urine. According to this theory, that charge plays a major role in the selective exclusion of albumin from the glomerular filtrate. A defect in this property results in [[nephrotic syndrome]] leading to albumin loss in the urine. Nephrotic syndrome patients are sometimes given albumin to replace the lost albumin.


==General characteristics==
== Structure ==
{{main|Albumin}}
The general structure of albumin is characterized by several long [[alpha helix|α helices]] allowing it to maintain a relatively static shape, which is essential for regulating blood pressure.


Albumin is negatively charged. The [[glomerular basement membrane]] is also negatively charged; some studies suggest that this prevents the filtration of albumin in the urine. According to this theory, that charge plays a major role in the selective exclusion of albumin from the glomerular filtrate, a defect in this property results in [[nephrotic syndrome]]. Thus, there is more albumin loss in the urine. Nephrotic syndrome patients are sometimes given albumin to replace the lost albumin.
Serum albumin contains eleven distinct binding domains for hydrophobic compounds. One [[hemin]] and six long-chain [[fatty acid]]s can bind to serum albumin at the same time.<ref name="pmid12846933">{{cite journal | vauthors = Zunszain PA, Ghuman J, Komatsu T, Tsuchida E, Curry S | title = Crystal structural analysis of human serum albumin complexed with hemin and fatty acid | journal = BMC Structural Biology | volume = 3 | issue =  | pages = 6 | date = July 2003 | pmid = 12846933 | pmc = 166163 | doi = 10.1186/1472-6807-3-6 }}</ref>
{|
|{{Infobox protein family
| Symbol = Serum_albumin
| Name = Serum albumin family
| image = PDB 1ao6 EBI.jpg
| width =
| caption = Structure of human serum albumin.<ref>{{cite journal | vauthors = Sugio S, Kashima A, Mochizuki S, Noda M, Kobayashi K | title = Crystal structure of human serum albumin at 2.5 A resolution | journal = Protein Engineering | volume = 12 | issue = 6 | pages = 439–46 | date = June 1999 | pmid = 10388840 | doi = 10.1093/protein/12.6.439 }}</ref>
| Pfam = PF00273
| Pfam_clan = CL0282
| InterPro = IPR014760
| SMART = SM00103
| PROSITE = PS51438
| SCOP = 1ao6
| TCDB =
| OPM family =
| OPM protein =
| PDB = {{PDB2|1ao6}}, {{PDB2|1bj5}}, {{PDB2|1bke}}, {{PDB2|1bm0}}, {{PDB2|1e78}}, {{PDB2|1e7a}}, {{PDB2|1e7b}}, {{PDB2|1e7c}}, {{PDB2|1e7e}}, {{PDB2|1e7f}}, {{PDB2|1e7g}}, {{PDB2|1e7h}}, {{PDB2|1e7i}}, {{PDB2|1gni}}, {{PDB2|1gnj}}, {{PDB2|1h9z}}, {{PDB2|1ha2}}, {{PDB2|1hk1}}, {{PDB2|1hk2}}, {{PDB2|1hk3}}, {{PDB2|1hk4}}, {{PDB2|1hk5}}, {{PDB2|1j78}}, {{PDB2|1j7e}}, {{PDB2|1kw2}}, {{PDB2|1kxp}}, {{PDB2|1lot}}, {{PDB2|1ma9}}, {{PDB2|1n5u}}, {{PDB2|1o9x}}, {{PDB2|1tf0}}, {{PDB2|1uor}}, {{PDB2|1ysx}}, {{PDB2|2bx8}}, {{PDB2|2bxa}}, {{PDB2|2bxb}}, {{PDB2|2bxc}}, {{PDB2|2bxd}}, {{PDB2|2bxe}}, {{PDB2|2bxf}}, {{PDB2|2bxg}}, {{PDB2|2bxh}}, {{PDB2|2bxi}}, {{PDB2|2bxk}}, {{PDB2|2bxl}}, {{PDB2|2bxm}}, {{PDB2|2bxn}}, {{PDB2|2bxo}}, {{PDB2|2bxp}}, {{PDB2|2bxq}}, {{PDB2|2i2z}}, {{PDB2|2i30}}, {{PDB2|2vdb}}, {{PDB2|2vue}}, {{PDB2|2vuf}}, {{PDB2|3b9l}}, {{PDB2|3b9m}}
}}
|}


Because smaller animals (for example rats) function at a lower [[blood pressure]], they need less [[oncotic pressure]] to balance this, and thus need less albumin to maintain proper fluid distribution.
== Types ==
Serum albumin is widely distributed in mammals. 
* The human version is [[human serum albumin]].
* [[Bovine serum albumin]], or BSA, is commonly used in immunodiagnostic procedures, clinical chemistry reagents, cell culture media, protein chemistry research (including venom toxicity), and [[molecular biology]] laboratories (usually to leverage its non-specific protein binding properties).


Serum albumin contains eleven distinct binding domains for hydrophobic compounds. One [[hemin]] and six long-chain [[fatty acid]]s can bind to serum albumin at the same time <ref name="">
== See also ==
BMC Structural Biology 2003, 3(1):6 2003. ''Crystal structural analysis of human serum albumin complexed with hemin and fatty acid''. Zunszain, Patricia A Ghuman, Jamie Komatsu, Teruyuki Tsuchida, Eishun Curry, Stephen doi: 10.1186/1472-6807-3-6 PMID 12846933 [http://www.biomedcentral.com/1472-6807/3/6 online]</ref>.
* [[Human serum albumin]]
* [[Bovine serum albumin]]
* [[Blood plasma fractionation]]
* [[Chromatography in blood processing]]
* [[Lactalbumin]]
* [[Ovalbumin]]


== References ==
== References ==
<references/>
{{Reflist}}


==External Links==
== External links ==
* [http://macromoleculeinsights.com/albumin.php The Serum Albumin Protein]
* [http://www.pdb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb37_1.html RCSB Protein Data Bank : Molecule of the Month – Serum Albumin]
* [http://albumin.althotas.com/ Albumin binding prediction]


{{PDB Gallery|geneid=213}}
{{Albumins}}
{{Albumins}}
{{Nuclear receptor modulators}}


[[Category:Proteins]]
[[Category:Blood proteins]]
[[Category:Blood]]
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Latest revision as of 12:10, 10 January 2019

This article is about the family of mammalian albumin proteins. For the human variant, see human serum albumin. For the cow variant, see bovine serum albumin. For the chicken variant, see conalbumin.
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Serum albumin, often referred to simply as blood albumin, is an albumin (a type of globular protein) found in vertebrate blood. Human serum albumin is encoded by the ALB gene.[1][2][3] Other mammalian forms, such as bovine serum albumin, are chemically similar.

Serum albumin is produced by the liver, occurs dissolved in blood plasma and is the most abundant blood protein in mammals. Albumin is essential for maintaining the oncotic pressure needed for proper distribution of body fluids between blood vessels and body tissues; without albumin, the high pressure in the blood vessels would force more fluids out into the tissues. It also acts as a plasma carrier by non-specifically binding several hydrophobic steroid hormones and as a transport protein for hemin and fatty acids. Too much or too little circulating serum albumin may be harmful. Albumin in the urine usually denotes the presence of kidney disease. Occasionally albumin appears in the urine of normal persons following long standing (postural albuminuria).

Function

Albumin functions primarily as a carrier protein for steroids, fatty acids, and thyroid hormones in the blood and plays a major role in stabilizing extracellular fluid volume by contributing to oncotic pressure (known also as colloid osmotic pressure) of plasma.

Because smaller animals (for example rats) function at a lower blood pressure, they need less oncotic pressure to balance this[citation needed], and thus need less albumin to maintain proper fluid distribution.

Synthesis

Albumin is synthesized in the liver as preproalbumin which has an N-terminal peptide that is removed before the nascent protein is released from the rough endoplasmic reticulum. The product, proalbumin, is in turn cleaved in the Golgi vesicles to produce the secreted albumin.[3]

Properties

Albumin is a globular, water-soluble, un-glycosylated serum protein of approximate molecular weight of 65,000 Daltons.

Albumin (when ionized in water at pH 7.4, as found in the body) is negatively charged. The glomerular basement membrane is also negatively charged in the body; some studies suggest that this prevents the filtration of albumin in the urine. According to this theory, that charge plays a major role in the selective exclusion of albumin from the glomerular filtrate. A defect in this property results in nephrotic syndrome leading to albumin loss in the urine. Nephrotic syndrome patients are sometimes given albumin to replace the lost albumin.

Structure

Main article: Albumin

The general structure of albumin is characterized by several long α helices allowing it to maintain a relatively static shape, which is essential for regulating blood pressure.

Serum albumin contains eleven distinct binding domains for hydrophobic compounds. One hemin and six long-chain fatty acids can bind to serum albumin at the same time.[4]

Serum albumin family
File:PDB 1ao6 EBI.jpg
Structure of human serum albumin.[5]
Identifiers
SymbolSerum_albumin
PfamPF00273
Pfam clanCL0282
InterProIPR014760
SMARTSM00103
PROSITEPS51438
SCOP1ao6
SUPERFAMILY1ao6

Types

Serum albumin is widely distributed in mammals.

  • The human version is human serum albumin.
  • Bovine serum albumin, or BSA, is commonly used in immunodiagnostic procedures, clinical chemistry reagents, cell culture media, protein chemistry research (including venom toxicity), and molecular biology laboratories (usually to leverage its non-specific protein binding properties).

See also

References

  1. ↑ Hawkins JW, Dugaiczyk A (1982). "The human serum albumin gene: structure of a unique locus". Gene. 19 (1): 55–8. doi:10.1016/0378-1119(82)90188-3. PMID 6292049.
  2. ↑ Harper ME, Dugaiczyk A (July 1983). "Linkage of the evolutionarily-related serum albumin and alpha-fetoprotein genes within q11-22 of human chromosome 4". American Journal of Human Genetics. 35 (4): 565–72. PMC 1685723. PMID 6192711.
  3. ↑ 3.0 3.1 "Entrez Gene: albumin".
  4. ↑ Zunszain PA, Ghuman J, Komatsu T, Tsuchida E, Curry S (July 2003). "Crystal structural analysis of human serum albumin complexed with hemin and fatty acid". BMC Structural Biology. 3: 6. doi:10.1186/1472-6807-3-6. PMC 166163. PMID 12846933.
  5. ↑ Sugio S, Kashima A, Mochizuki S, Noda M, Kobayashi K (June 1999). "Crystal structure of human serum albumin at 2.5 A resolution". Protein Engineering. 12 (6): 439–46. doi:10.1093/protein/12.6.439. PMID 10388840.

External links

Retrieved from "https://www.wikidoc.org/index.php?title=Serum_albumin&oldid=1526501"