|Ref Sequence ID||NP_776414.1|
|Protein Existence Status||Reviewed: Experimental evidence at protein level|
|Presence in other biological fluids/tissue/cells||Liver, blood, kidney, developing gut, vessel epithelia of the umbilical cord, pancreas|
|Protein Function||codes for a polypeptide that gives rise to two different secreted proteins - α1-microglobulin and bikunin. Protein AMBP is a precursor of a heme-binding protein that counteracts the damaging effects of free hemoglobin, which may be related to the presence of free hemoglobin in CSF.|
|Biochemical Properties||α1-microglobulin binds a chromophore formed during heme-binding and degradation; bikunin is a proteinase inhibitor of the inter-a-inhibitor family|
|Significance in milk||source of α trypsin inhibitors in milk;|
|PTMs||Cleavage on pair of basic residues, Disulfide bond formation, Glycosylation at Asn|
| Site(s) of PTM(s) |
|Predicted Disorder Regions||187-223|
|TM Helix Prediction||No TM helices|
|Significance of PTMs||3-hydroxykynurenine, an oxidized tryptophan metabolite that is common in biological fluids, reacts with Cys-53, Lys-111, Lys-137, and Lys-149 to form heterogeneous polycyclic chromophores including hydroxanthommatin. The reaction by alpha-1-microglobulin is autocatalytic. The chromophore can react with accessible cysteines forming non-reducible thioether cross-links with other molecules of alpha-1-microglobulin or with other proteins such as Ig alpha-1 chain C region. Heavy chains are interlinked with bikunin via a chondroitin 4-sulfate bridge to the their C-terminal aspartate.|
|Bibliography||1. Sánchez, D., Martínez, S., Lindqvist, A., Åkerström, B., & Falkenberg, C. (2002). Expression of the AMBP gene transcript and its two protein products, α1-microglobulin and bikunin, in mouse embryogenesis. Mechanisms of Development, 117(1–2), 293–298. https://doi.org/10.1016/S0925-4773(02)00202-2. |
2. Allhorn, M., Berggård, T., Nordberg, J., Olsson, M. L., & Akerström, B. (2002). Processing of the lipocalin alpha(1)-microglobulin by hemoglobin induces heme-binding and heme-degradation properties. Blood, 99(6), 1894–1901. https://doi.org/10.1182/blood.v99.6.1894.
3. Lindqvist, A., Rouet, P., Salier, J. P., & Akerström, B. (1999). The alpha1-microglobulin/bikunin gene: characterization in mouse and evolution. Gene, 234(2), 329–336. https://doi.org/10.1016/s0378-1119(99)00191-2. 4.van den Berg CB, Duvekot JJ, Güzel C, Hansson SR, de Leeuw TG, Steegers EA, Versendaal J, Luider TM, Stoop MP. Elevated levels of protein AMBP in cerebrospinal fluid of women with preeclampsia compared to normotensive pregnant women. Proteomics Clin Appl. 2017 Jan;11(1-2). doi: 10.1002/prca.201600082. Epub 2016 Oct 24. PMID: 27615121.