Primary Information
BoMiProt ID	Bomi99
Protein Name	AMBP
Organism	Bos taurus
Uniprot ID	P00978
Milk Fraction	Whey
Ref Sequence ID	NP_776414.1
Aminoacid Length	352
Molecular Weight	39235
FASTA Sequence	Download
Gene Name	AMBP
Gene ID	280996
Protein Existence Status	Reviewed: Experimental evidence at protein level
Secondary Information
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) N-glycosylation, O-glycosylation, Phosphorylation
Predicted Disorder Regions	187-223
DisProt Annotation
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.