β2 microglobulin also known as B2M is a component of MHC class I molecules, MHC class I molecules have α1, α2, and α3 proteins which are present on all nucleated cells (excludes red blood cells). In humans, the β2 microglobulin protein is encoded by the B2M gene. β2 microglobulin associates not only with the alpha chain of MHC class I molecules, but also with class I-like molecules such as CD1 (5 genes in humans), MR1, the neonatal Fc receptor (FcRn), and Qa-1 (a form of alloantigen). Nevertheless, the β2 microglobulin gene is outside of the MHC (HLA) locus, on a different chromosome. An additional function is association with the HFE protein, together regulating the expression of hepcidin in the liver which targets the iron transporter ferroportin on the basolateral membrane of enterocytes and cell membrane of macrophages for degradation resulting in decreased iron uptake from food and decreased iron release from recycled red blood cells in the MPS (mononuclear phagocyte system) respectively. Loss of this function causes iron excess and hemochromatosis. In cytomegalovirus infection, a viral protein binds to β2 microglobulin, preventing assembly of MHC class I molecules and their transport to the plasma membrane.
Background References
1. Zhao Y et al. beta(2)-Microglobulin coaggregates with Abeta and contributes to amyloid pathology and cognitive deficits in Alzheimer\'s disease model mice. Nat Neurosci. 2023 Jul
2. Wang C et al. The immune-related role of beta-2-microglobulin in melanoma. Front Oncol. 2022 Aug
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (HA723430) at 1/2,000 dilution was used in primary antibody dilution (K1803) at 4℃ overnight. Goat Anti-Rabbit IgG - HRP Secondary Antibody (HA1001) at 1/50,000 dilution was used for 1 hour at room temperature.
Immunohistochemical analysis of paraffin-embedded human lymph node tissue with Rabbit anti-beta 2 Microglobulin antibody (HA723430) at 1/1,000 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA723430) at 1/1,000 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
Immunohistochemical analysis of paraffin-embedded human kidney tissue with Rabbit anti-beta 2 Microglobulin antibody (HA723430) at 1/1,000 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA723430) at 1/1,000 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
☑ Relative expression (RE)
Immunocytochemistry analysis of HeLa (positive) and SH-SY5Y (negative) labeling beta 2 Microglobulin with Rabbit anti-beta 2 Microglobulin antibody (HA723430) at 1/1,000 dilution.
Cells were fixed in 4% paraformaldehyde for 15 minutes at room temperature, permeabilized with 0.1% Triton X-100 in PBS for 15 minutes at room temperature, then blocked with 1% BSA in 10% negative goat serum for 1 hour at room temperature. Cells were then incubated with Rabbit anti-beta 2 Microglobulin antibody (HA723430) at 1/1,000 dilution in 1% BSA in PBST overnight at 4 ℃. Goat Anti-Rabbit IgG H&L (iFluor™ 488, HA1121) was used as the secondary antibody at 1/1,000 dilution. PBS instead of the primary antibody was used as the secondary antibody only control. Nuclear DNA was labelled in blue with DAPI.
Beta tubulin (HA601187, red) was stained at 1/100 dilution overnight at +4℃. Goat Anti-Mouse IgG H&L (iFluor™ 594, HA1126) was used as the secondary antibody at 1/1,000 dilution.
☑ Relative expression (RE)
Flow cytometric analysis of SH-SY5Y (left, negative) and HeLa (right, positive) cells labeling beta 2 Microglobulin.
Cells were washed twice with cold PBS and resuspend. Then stained with the primary antibody (HA723430, 1/1,000) (red) compared with Rabbit IgG Isotype Control (green). After incubation of the primary antibody at +4℃ for an hour, the cells were stained with a iFluor™ 488 conjugate-Goat anti-Rabbit IgG Secondary antibody (HA1121) at 1/1,000 dilution for 30 minutes at +4℃. Unlabelled sample was used as a control (cells without incubation with primary antibody; black).
beta 2 Microglobulin was immunoprecipitated from 0.2 mg Raji cell lysate with HA723430 at 2 µg/10 µl beads. Western blot was performed from the immunoprecipitate using HA723430 at 1/2,000 dilution. HRP Conjugated Anti-Rabbit IgG for IP Nano-secondary antibody at 1/5,000 dilution was used for 1 hour at room temperature.
Lane 1: Raji cell lysate (input) Lane 2: HA723430 IP in Raji cell lysate Lane 3: Rabbit IgG instead of HA723430 in Raji cell lysate