Serum albumin

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

Serum albumin family
	Structure of human serum albumin.
Identifiers
Symbol	Serum_albumin
Pfam	PF00273
Pfam clan	CL0282
InterPro	IPR014760
SMART	SM00103
PROSITE	PS51438
SCOP	1ao6
SUPERFAMILY	1ao6
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

Albumin
Albumin
	PDB rendering based on 1e7h.
Available structures
PDB	Ortholog search: PDBe, RCSB
List of PDB id codes
	1AO6, 1BJ5, 1BKE, 1BM0, 1E78, 1E7A, 1E7B, 1E7C, 1E7E, 1E7F, 1E7G, 1E7H, 1E7I, 1GNI, 1GNJ, 1H9Z, 1HA2, 1HK1, 1HK2, 1HK3, 1HK4, 1HK5, 1N5U, 1O9X, 1TF0, 1UOR, 1YSX, 2BX8, 2BXA, 2BXB, 2BXC, 2BXD, 2BXE, 2BXF, 2BXG, 2BXH, 2BXI, 2BXK, 2BXL, 2BXM, 2BXN, 2BXO, 2BXP, 2BXQ, 2ESG, 2I2Z, 2I30, 2N0X, 2VDB, 2VUE, 2VUF, 2XSI, 2XVQ, 2XVU, 2XVV, 2XVW, 2XW0, 2XW1, 2YDF, 3A73, 3B9L, 3B9M, 3CX9, 3JQZ, 3JRY, 3LU6, 3LU7, 3LU8, 3SQJ, 3TDL, 3UIV, 4BKE, 4E99, 4EMX, 4G03, 4G04, 4HGK, 4HGM, 4IW1, 4IW2, 4K2C, 4K71, 4L8U, 4L9K, 4L9Q, 4LA0, 4LB2, 4LB9, 4N0F, 4N0U, 4S1Y
Identifiers
Symbols	ALB ; ANALBA; FDAH; PRO0883; PRO0903; PRO1341
External IDs	OMIM: 103600 MGI: 87991 HomoloGene: 405 ChEMBL: 3253 GeneCards: ALB Gene
Gene ontology
Molecular function	• DNA binding; • fatty acid binding; • copper ion binding; • protein binding; • drug binding; • toxic substance binding; • antioxidant activity; • oxygen binding; • pyridoxal phosphate binding; • chaperone binding;
Cellular component	• extracellular region; • extracellular space; • nucleus; • platelet alpha granule lumen; • myelin sheath; • protein complex; • extracellular exosome; • blood microparticle;
Biological process	• retina homeostasis; • platelet degranulation; • transport; • receptor-mediated endocytosis; • blood coagulation; • bile acid metabolic process; • cellular response to starvation; • bile acid and bile salt transport; • hemolysis by symbiont of host erythrocytes; • platelet activation; • lipoprotein metabolic process; • negative regulation of apoptotic process; • negative regulation of programmed cell death; • sodium-independent organic anion transport; • small molecule metabolic process; • maintenance of mitochondrion location; • transmembrane transport;
	Sources: Amigo / QuickGO
RNA expression pattern
	More reference expression data
Orthologs
Species	Human
Entrez	213
Ensembl	ENSG00000163631
UniProt	P02768
RefSeq (mRNA)	NM_000477
RefSeq (protein)	NP_000468
Location (UCSC)	Chr 4:; 73.4 – 73.42 Mb
PubMed search	[1]
	v; t; e;

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, 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

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]

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).