| Structural highlights
Disease
ALBU_HUMAN Defects in ALB are a cause of familial dysalbuminemic hyperthyroxinemia (FDH) [MIM:103600. FDH is a form of euthyroid hyperthyroxinemia that is due to increased affinity of ALB for T(4). It is the most common cause of inherited euthyroid hyperthyroxinemia in Caucasian population.[1] [2] [3] [4]
Function
ALBU_HUMAN Serum albumin, the main protein of plasma, has a good binding capacity for water, Ca(2+), Na(+), K(+), fatty acids, hormones, bilirubin and drugs. Its main function is the regulation of the colloidal osmotic pressure of blood. Major zinc transporter in plasma, typically binds about 80% of all plasma zinc.[5]
Publication Abstract from PubMed
The long circulating half-life of serum albumin, the most abundant protein in mammalian plasma, derives from pH-dependent endosomal salvage from degradation, mediated by the neonatal Fc receptor (FcRn). Using yeast display, we identified human serum albumin (HSA) variants with increased affinity for human FcRn at endosomal pH, enabling us to solve the crystal structure of a variant HSA/FcRn complex. We find an extensive, primarily hydrophobic interface stabilized by hydrogen-bonding networks involving protonated histidines internal to each protein. The interface features two key FcRn tryptophan side chains inserting into deep hydrophobic pockets on HSA that overlap albumin ligand binding sites. We find that fatty acids (FAs) compete with FcRn, revealing a clash between ligand binding and recycling, and that our high-affinity HSA variants have significantly increased circulating half-lives in mice and monkeys. These observations open the way for the creation of biotherapeutics with significantly improved pharmacokinetics.
Crystal structure of an HSA/FcRn complex reveals recycling by competitive mimicry of HSA ligands at a pH-dependent hydrophobic interface.,Schmidt MM, Townson SA, Andreucci AJ, King BM, Schirmer EB, Murillo AJ, Dombrowski C, Tisdale AW, Lowden PA, Masci AL, Kovalchin JT, Erbe DV, Wittrup KD, Furfine ES, Barnes TM Structure. 2013 Nov 5;21(11):1966-78. doi: 10.1016/j.str.2013.08.022. Epub 2013, Oct 10. PMID:24120761[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Sunthornthepvarakul T, Angkeow P, Weiss RE, Hayashi Y, Refetoff S. An identical missense mutation in the albumin gene results in familial dysalbuminemic hyperthyroxinemia in 8 unrelated families. Biochem Biophys Res Commun. 1994 Jul 29;202(2):781-7. PMID:8048949
- ↑ Rushbrook JI, Becker E, Schussler GC, Divino CM. Identification of a human serum albumin species associated with familial dysalbuminemic hyperthyroxinemia. J Clin Endocrinol Metab. 1995 Feb;80(2):461-7. PMID:7852505
- ↑ Wada N, Chiba H, Shimizu C, Kijima H, Kubo M, Koike T. A novel missense mutation in codon 218 of the albumin gene in a distinct phenotype of familial dysalbuminemic hyperthyroxinemia in a Japanese kindred. J Clin Endocrinol Metab. 1997 Oct;82(10):3246-50. PMID:9329347
- ↑ Sunthornthepvarakul T, Likitmaskul S, Ngowngarmratana S, Angsusingha K, Kitvitayasak S, Scherberg NH, Refetoff S. Familial dysalbuminemic hypertriiodothyroninemia: a new, dominantly inherited albumin defect. J Clin Endocrinol Metab. 1998 May;83(5):1448-54. PMID:9589637
- ↑ Lu J, Stewart AJ, Sadler PJ, Pinheiro TJ, Blindauer CA. Albumin as a zinc carrier: properties of its high-affinity zinc-binding site. Biochem Soc Trans. 2008 Dec;36(Pt 6):1317-21. doi: 10.1042/BST0361317. PMID:19021548 doi:10.1042/BST0361317
- ↑ Schmidt MM, Townson SA, Andreucci AJ, King BM, Schirmer EB, Murillo AJ, Dombrowski C, Tisdale AW, Lowden PA, Masci AL, Kovalchin JT, Erbe DV, Wittrup KD, Furfine ES, Barnes TM. Crystal structure of an HSA/FcRn complex reveals recycling by competitive mimicry of HSA ligands at a pH-dependent hydrophobic interface. Structure. 2013 Nov 5;21(11):1966-78. doi: 10.1016/j.str.2013.08.022. Epub 2013, Oct 10. PMID:24120761 doi:http://dx.doi.org/10.1016/j.str.2013.08.022
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