High impact information on B2M

• T cell precursor migration towards beta 2-microglobulin is involved in thymus colonization of chicken embryos [1].
• beta 2-microglobulin (beta 2m) attracts hemopoietic precursors from chicken bone marrow cells in vitro [1].
• In contrast these beta 2m responsive precursors did not colonize embryonic bursa, i.e. differentiate into B lymphocytes [1].
• During chicken embryogenesis, peaks of beta 2m transcripts and of free beta 2m synthesis can only be detected in the thymus [1].
• The peak of free beta 2m synthesis in the thymus and the increase of beta 2m responding bone marrow cells both occur concomitantly with the second wave of thymus colonization in chicken embryo, facts which suggest that beta 2m mediated chemotaxis is involved in the second wave [1].

Biological context of B2M

• The chicken beta 2-microglobulin gene is located on a non-major histocompatibility complex microchromosome: a small, G+C-rich gene with X and Y boxes in the promoter [2].
• beta 2-Microglobulin is an essential subunit of major histocompatibility complex (Mhc) class I molecules, which present antigenic peptides to T lymphocytes [2].
• The promoter region is particularly G+C-rich and contains, in addition to interferon regulatory elements, potential S/W, X, and Y boxes that were originally described for mammalian class II but not class I alpha or beta 2-microglobulin genes [2].
• The chicken beta 2-microglobulin gene has a similar genomic organization but smaller introns and higher G+C content than mammalian beta 2-microglobulin genes [2].
• Amino acid sequences and structures of chicken and turkey beta 2-microglobulin [3].

Anatomical context of B2M

• The method demonstrates the loss of B2M from the cell membranes of malignant eccrine poromas , and this is correlated with the histopathologic and clinical criteria of malignancy [4].
• The cell population responding to beta 2m increases during the second period of thymus colonization, which takes place at days 12-14 of incubation [1].
• N-CAM of the chicken for neuronal organogenesis already possesses four beta 2-microglobulin-like domains and it is this domain from which the adaptive immune system sprang [5].
• Erythrocytes and peripheral blood lymphocyte extracts contained 8.0 and 5.1 micrograms/10(9) cells respectively whereas all other tissues examined expressed greater than 2.0 micrograms/g. The beta 2m content in turkey serum was 192.5 micrograms/ml [6].

Associations of B2M with chemical compounds

• Identification of turkey beta 2m was based upon NH2-terminal primary structure analysis [7].
• A competitive binding radioimmunoassay (RIA) was developed utilizing 125I-labeled turkey beta 2-microglobulin (beta 2m), rabbit anti-turkey beta 2m serum and polyethylene glycol for separation of bound and free antigen [6].

Analytical, diagnostic and therapeutic context of B2M

• Restriction fragment length polymorphisms from Mhc homozygous lines, Mhc congenic lines, and backcross families, as well as in situ hybridization, show that the beta 2-microglobulin gene is located on a microchromosome different from the one that contains the chicken Mhc [2].
• The higher apparent Mr obtained for the avian beta 2-microglobulins as compared to human beta 2-microglobulin by SDS-PAGE is not understood [3].
• Type 2 molecules migrated to the basic end of isoelectric focusing gels, exhibited multiple isomorphic variants, and were associated with a smaller polypeptide of approximately 11 to 12 Kd assumed to be beta-2-microglobulin [8].
• The molecular weight distribution of turkey beta 2m in serum determined by gel permeation chromatography consisted of a minor component of approximately 60,000 daltons and a major fraction eluting at a position characteristic of free beta 2m [6].
• The NH2-terminal primary structure of turkey beta 2m is: NH2-Lys-Ile-Glu-Val-Tyr-Ile-Lys-. The purity of the isolated protein was confirmed by two-dimensional polyacrylamide gel electrophoresis, immunodiffusion and immunoelectrophoresis [7].

References