AMBP

Alpha 1-microglobulin (A1M), a member of the lipocalin superfamily (specifically, the kernal lipocalins), is a low molecular weight protein found in plasma. Present in both plasma and the extravascular compartments of all organs, A1M is found in a variety of vertebrates, including mammals, birds, amphibians, and fish. Primarily synthesized in the liver and kidneys, A1M is characterized by three lysyl residues near the opening of its lipocalin pocket. These residues exhibit a yellow-brown modification resulting from the binding and breakdown of heme and kynurenin, a metabolite of tryptophan. A1M possesses reductase and dehydrogenase properties with broad substrate specificity due to its free cysteine side-chain located on a flexible loop. Glycosylation of A1M involves three distinct carbohydrate chains: two complex carbohydrates N-linked to asparagines at positions 17 and 96, and a simple carbohydrate O-linked to threonine at position 5. These carbohydrates constitute 22% of the protein's total molecular weight, and the specific glycosylation patterns vary between species. A1M exists in two forms: a free form and a form complexed with other macromolecules. In humans, A1M complexes with immunoglobulin A (IgA), while in rats, it complexes with alpha-1-inhibitor-3. The free form of A1M exhibits significant charge heterogeneity (hence its alternative name, protein HC) and is closely associated with a chromophore. This monomeric form consists of a single polypeptide chain with 188 residues and three cysteines. Two of these cysteines (residues 75 and 173) form a conserved intra-molecular disulfide bond, while the chromophoric group is covalently linked to the free cysteine at position 34. While A1M binds retinol as a major ligand, this binding is likely distinct from its covalent association with the chromophore. Approximately half of the A1M in human plasma (around 0.03mg/ml) forms a 1:1 complex with about 5% of plasma immunoglobulin A. These macromolecular complexes, with a molecular weight of 200,000 and a plasma concentration of 0.3mg/ml, can exhibit antibody activity and influence several biological actions of free A1M. Initially discovered in pathological human urine, A1M has been implicated in various protective functions, including defense against reactive oxygen species and oxidative damage caused by heme and kynurenin. There is also evidence suggesting a role for A1M in immune system regulation. Other functions attributed to A1M include inhibiting the stimulation of cultured lymphocytes by protein antigens, inducing lymphocyte cell division (a mitogenic effect that can be modulated by other plasma components), inhibiting neutrophil granulocyte migration in vitro, and suppressing chemotaxis.

Recombinant human AMBP, produced in E. coli, is a single, non-glycosylated polypeptide chain composed of 205 amino acids (residues 20-203). This protein has a molecular mass of 23.1 kDa. A 21 amino acid His-tag is fused to the N-terminus of AMBP, and the protein is purified using proprietary chromatographic techniques.

A clear, colorless solution that has been sterilized by filtration.

The AMBP solution (0.5mg/ml) is formulated in a buffer containing 20mM Tris-HCl (pH 8.0), 1mM DTT, 0.1M NaCl, and 10% glycerol.

For short-term storage (2-4 weeks), the AMBP solution should be stored at 4°C. For longer storage, it is recommended to freeze the solution at -20°C. Adding a carrier protein (0.1% HSA or BSA) is advisable for long-term storage. Repeated freezing and thawing of the solution should be avoided.

The purity of the AMBP protein is greater than 90%, as determined by SDS-PAGE analysis.

Alpha-1-microglobulin/bikunin precursor, HCP, ITIL, ITI, EDC1, HI30, IATIL, ITILC, UTI, A1M, bikunin, complex-forming glycoprotein heterogeneous in charge, growth-inhibiting protein 19, inter-alpha-trypsin inhibitor light chain, protein AMBP, protein HC, trypstatin, uristatin,
 uronic-acid-rich protein.

E.coli.

MGSSHHHHHH SSGLVPRGSH MGPVPTPPDN IQVQENFNIS RIYGKWYNLA IGSTCPWLKK IMDRMTVSTL VLGEGATEAE ISMTSTRWRK GVCEETSGAY EKTDTDGKFL YHKSKWNITM ESYVVHTNYD EYAIFLTKKF SRHHGPTITA KLYGRAPQLR ETLLQDFRVV AQGVGIPEDS IFTMADRGEC VPGEQEPEPI LIPRV.