α 1 -microglobulin

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α 1 -microglobulin
Mass / length primary structure 33 kilodaltons
Secondary to quaternary structure monomeric
Precursor Protein AMBP
Identifier
Gene name (s) AMBP, HCP, ITIL
External IDs

α 1 -microglobulin is a low molecular weight glycoprotein that plays a role in the identification of functional disorders of the kidney tubules (so-called tubulopathies). It is also known as Protein HC .

properties

The protein is mainly synthesized in the liver. The function of the protein is u. a. in the binding and degradation of the heme component of hemoglobin . If the tubules are damaged, an increased amount of α 1 -microglobulin is excreted in the urine, which makes the damage detectable. Due to the low molecular size of 33,000 Dalton , the protein is not retained in the glomerula , but excreted in the primary urine .

Biomarkers

If the tubules are damaged, the protein cannot be reabsorbed sufficiently so that more of it is excreted in the urine. In a way that is independent of this, increased excretion can also occur in the case of glomerular damage. This is because if the glomerular filtration is reduced, the concentration of α 1 -microglobulin in the serum increases . As a result, the protein in the remaining nephrons is excreted to a greater extent, so that the resorption capacity of the tubules is exceeded and an overflow proteinuria occurs. The urine concentration of α 1 -microglobulin is therefore a biomarker of kidney function. The urine concentration of α 1 -microglobulin is used as a marker to detect tubular damage to the kidney. Just like β 2 -microglobulin , it plays a role in the differential diagnosis of proteinuria.

All diseases that lead to dysfunction of the renal tubules can be associated with an increase in α 1 -microglobulin excretion. This includes the inflammation in the area of ​​the tubules, such as occur in interstitial nephritis or acute pyelonephritis . In addition, toxic damage to the kidneys, as z. B. after the administration of analgesics , cytostatics or aminoglycosides can occur via the tubular damage to an increase in α 1 -microglobulin in the urine.

Individual evidence

  1. ↑ J. Penders, JR Delanghe: Alpha 1-microglobulin: clinical laboratory aspects and applications. In: Clinica Chimica Acta . Volume 346, Number 2, August 2004, pp. 107-118, ISSN  0009-8981 . doi : 10.1016 / j.cccn.2004.03.037 . PMID 15256311 .
  2. ↑ L. Tejler, AO Grubb: A complex-forming glycoprotein heterogeneous in charge and present in human plasma, urine, and cerebrospinal fluid. In: Biochimica et Biophysica Acta . Volume 439, 1976, pp. 82-94, ISSN  0006-3002 . PMID 952962 .
  3. ^ W. Meining, A. Skerra: The crystal structure of human? (1) -microglobulin reveals a potential haem-binding site. In: The Biochemical journal . Volume 445, 2012, pp. 175-182, ISSN  1470-8728 . doi : 10.1042 / BJ20120448 . PMID 22512701 . PDF .
  4. ↑ T. Berggård, N. Thelin, C. Falkenberg, JJ Enghild, B. Akerström: Prothrombin , albumin and immunoglobulin A form covalent complexes with alpha1-microglobulin in human plasma . In: European Journal of Biochemistry . Volume 245, 1997, pp. 676-683. PMID 9183005 .
  5. ↑ CM O'Seaghdha, SJ Hwang, MG Larson, JB Meigs, RS Vasan, CS Fox: Analysis of a Urinary Biomarker Panel for Incident Kidney Disease and Clinical Outcomes. In: Journal of the American Society of Nephrology . 2013, 24: 1880-1884. doi : 10.1681 / ASN.2013010019 . PMID 23990678 .