Disease relevance of B2m

• Above a threshold of 100 mg/24 h, albuminuria induced by puromycin aminonucleoside (50 mg/kg) and Adriamycin (5 mg/kg) was associated with a marked increase in the urinary excretion of beta 2-microglobulin and cystatin C peaking at more than 100-fold the baseline levels [1].
• Furthermore, immune precipitates formed from soluble tumour extracts containing hepatoma D23 specific antigen with turkey anti-rat beta 2 microglobulin failed to generate a tumour-specific antibody response in syngeneic rats althouth a cross-reactive antiserum was produced following immunization of allogeneic rats with the immune precipitate [2].
• HLA-B27/beta2 microglobulin transgenic (TG) rats spontaneously develop T-cell-mediated colitis when colonized with normal commensal bacteria, but remain disease-free under germ-free conditions [3].
• At the end of the study, only the interaction with beta 2-microglobulin excretion was still evident; that with the urinary excretion of beta-N-acetylglucosaminidase and albumin having been masked by the chronic progressive nephrosis affecting most animals at that stage [4].
• These structures, antigenically related to AgB antigens, were not detected on plasmacytoma or hepatoma cells, nor did they display any antigenic similarity with rat beta 2-microglobulin [5].

High impact information on B2m

• Association of beta 2-microglobulin with p51 was confirmed by crosslinking in intestinal epithelial cell brush borders [6].
• This RNA contained functional FcRn transcripts as it encoded a beta 2-microglobulin-associated cell surface protein as determined by immunoprecipitation of biotinylated cell surface proteins with a polyclonal anti-FcRn specific antiserum [7].
• Beta 2-Microglobulin (beta 2m), a component of the major histocompatibility complex in chordates, has growth factor-like activity for cultured rat cells [8].
• Beta 2-microglobulin enhances insulin-like growth factor I receptor levels and synthesis in bone cell cultures [8].
• Amino acid composition of the purified molecule was compared by the S delta Q index of differences in composition to mammalian and non-mammalian Thy-1 glycoproteins, Ig, major histocompatibility complex-encoded polypeptides, beta 2-microglobulin, and other recognition molecules [9].

Chemical compound and disease context of B2m

• The increase in beta 2-microglobulin amount in rat urine and polyuria persisted until the 14th day after oxoplatinum administration [10].

Biological context of B2m

• Nucleotide sequence of rat beta 2-microglobulin cDNA [11].
• Tissue patterns of gene expression were analyzed by measuring mRNA levels and incorporation of radioactive amino acids for cystatin C and beta 2-microglobulin, the two extracellular proteins in the brain with the highest ratio of concentration in cerebrospinal fluid over that in blood plasma [12].
• The receptor shows a striking structural similarity to class I major histocompatibility complex (MHC) molecules, being composed of a related heavy chain and the identical light chain (beta 2-microglobulin) [13].
• During absorptive cell differentiation, gp50 and beta 2-microglobulin showed nearly identical patterns of increased expression that accompanied the development of the apical endocytic apparatus and terminal web [14].
• The IT45 cell line exported beta 2m through a constitutive pathway of secretion, as indicated by the kinetics of production and localization of intracellular beta 2m [15].

Anatomical context of B2m

• Other parts of the brain and testis contained lower levels of beta 2-microglobulin mRNA [12].
• The highest levels of beta 2-microglobulin mRNA were observed in liver and choroid plexus [12].
• Overproduction and secretion of beta 2-microglobulin by a rat thymic epithelial cell line that expresses MHC class I heavy chain [15].
• Although cells from the IT45 cell line expressed a much higher amount of beta 2m as compared to IT26 and NBT II cells (a rat bladder epithelial cell line), all three of these cell lines expressed the same amount of membrane and intracellular MHC class I heavy chain [15].
• However, absorptive cells in weanling rats expressed no detectable gp50 and only low levels of beta 2-microglobulin in the Golgi region and on the basolateral plasma membrane where class I antigens would likely reside [14].

Associations of B2m with chemical compounds

• The cDNA structure and expression analysis of the genes for the cysteine proteinase inhibitor cystatin C and for beta 2-microglobulin in rat brain [12].
• We have examined the urinary excretion of albumin and of 2 low-M(r) proteins, beta 2-microglobulin and cystatin C, in rats treated with toxins affecting primarily the glomerulus (puromycin amino-nucleoside and Adriamycin) or the tubule (mercuric chloride and maleic acid) [1].
• Tubular function, namely, phosphate reabsorption and beta 2-microglobulin excretion, was improved in rats with chronic PAN treated with the vitamin E-enriched diet [16].
• The Fc receptor resembles the major histocompatibility complex class I antigens in that it consists of two subunits: a transmembrane glycoprotein (gp50) in association with beta 2-microglobulin [14].
• Bleomycin treatment of rat lung fibroblast cultures resulted in an increase of total cellular transforming growth factor-beta (TGF-beta) mRNA and increased secretion of TGF-beta protein into the conditioned media. beta 2-Microglobulin was measured as an mRNA that did not increase with bleomycin treatment [17].

Physical interactions of B2m

• Beta-2-microglobulin also bound to fibronectin but this complex was dissociated with 1 M urea [18].

Other interactions of B2m

• MHC class I, beta2 microglobulin, and the INF-gamma receptor are upregulated in aged motoneurons [19].
• We presently describe interactions between beta 2m and insulin-like growth factor I (IGF I) in osteoblast-enriched cultures. beta 2m increased DNA synthesis and was synergistic with IGF I [8].
• The proteins studied varied in radius from 16.2 A (Beta 2-microglobulin) to 90 A (alpha 2-macroglobulin) [20].
• The water-soluble RT1-A molecule had a discrete heavy chain of 40 kD, linked noncovalently to beta 2 microglobulin [21].
• Hybridization experiments with beta2-microglobulin and beta-actin cDNA species reveal an expected subcellular distribution pattern of the mRNA species and a non-clustered appearance [22].

Analytical, diagnostic and therapeutic context of B2m

• Affinity labeling revealed that beta 2m enhanced IGF I receptor number, and Northern analysis and radioimmunoassay showed that beta 2m increased steady state IGF I transcripts and medium IGF I polypeptide levels [8].
• Prolonged survival of heart allografts in rats treated with antisera to beta2-microglobulin [23].
• After a peripheral axotomy, the motoneurons show a clear upregulation of beta2-microglobulin mRNA [24].
• Effects of direct hemoperfusion with a beta2-microglobulin adsorption column on hypercytokinemia in rats [25].
• Appearance of beta-2-microglobulin in rat hypothalamic magnocellular neurons after hypophysectomy [26].

References