| Description | Absorbance: A412 nm = 1.10 at 1/50 dilution in deionized waterGeneral DescriptionEr are rabbit red blood cells which have been washed free of rabbit plasmaproteins, but they are not coated with antibodies as is done with EA. These cells have traditionally been used as cells that spontaneously Absorbance: A412 nm = 1.10 at 1/50 dilution in deionized waterGeneral DescriptionEr are rabbit red blood cells which have been washed free of rabbit plasmaproteins, but they are not coated with antibodies as is done with EA. These cells have traditionally been used as cells that spontaneously activate the human alternative complement pathway in serum samples (Morgan, B.P. (2000; Dodds, A.W. and Sim, R.B. (1997)). Most human serum samples have small amounts of natural antibodies (usually IgG) to rabbit antigens and at high concentrations of serum these will agglutinate Er. This will activate the classical pathway if not blocked. Blocking the classical pathway is usually accomplished with 3 to 13 mM MgEGTA.Er are supplied at assay-ready concentrations in the traditional buffer used for APH50 assays (GVB°) which lacks metal ions. They can usually be used for 2 weeks after preparation. They are shipped cold, but are not harmed by extended periods at room temperature (note that they circulate 60+ days at 37℃in vivo). They should be washed once before each use (3-5 min at 500 to 1000 x g at 4℃) and resuspended in GVB° to reduce background and readjust their concentration. This procedure may also be used to concentrate the cells.Physical CharacteristicsEr are natural uncoated (non-opsonized) rabbit erythrocytes.AssaysAlthough the APH50 titer is widely used and serves as the primary test for alternative pathway complement activity, the APH50 assay procedure is not entirely standardized. In research labs there are as many procedures as there are labs, but all are basically similar and give useful results. The main difference between the classical pathway assays for CH50 determination and the alternative pathway assays for APH50 is the concentration of serum required. Alternative pathway activity becomes ineffective at dilutions of serum beyond 1/10 to 1/30. In contrast, CH50 titers are performed in the range 1/100 to 1/500 dilution. Dilution silences the alternative pathway in CH50 titers, but APH50 measurements would be overwhelmed by the classical pathway if this pathway were not blocked. Blocking of alternative pathway activity may be accomplished by using serum depleted of factor B or D or most conveniently by adding 3 to 13 mM MgEGTA (final concentration) to the assays which completely inhibits the classical pathway by chelating calcium ions and dissociating C1. Briefly, a complement-containing serum sample is diluted such that the final dilutions in the assay are in the range from 1/2 to 1/20. Controls include two tubes with no complement for the 0% lysis background and two tubes for 100% lysis. Assay tubes should be set up on ice. The assays are performed in 200 µL containing 4 to 60 µL of test serum, 10 µL 0.1 M MgEGTA, GVB°, and 50 µL Er. The assays are mixed and placed in a 37℃ water bath with remixing at approximately 10 min intervals. After 30 min, 2 mL of cold GVBE is added, mixed and the unlysed cells are spun down (500-1000 x g for 3 min). The absorbance of the supernatant should be determined at 412 nm in a 1 cm cuvette and the percentage of specific lysis calculated after subtracting the background and dividing by the 100% lysis control. The data is plotted as percent lysis on the y axis and µL serum on the x axis. The APH50 value of the complement sample is calculated from the amount of serum needed to cause lysis of 50% of the cells. For example, if it takes 12 µL NHS to lyse 50% of the cells then this serum would contain 83 AHP50 units/mL (1000 µL /12 µL = 83 units/mL). It should be noted that somewhat different APH50 values can be obtained on what should be identical samples. This is the result of the vast number of variables involved in APH50 determinations including the fact that each batch of rabbit erythrocytes is slightly different.ApplicationsEr cells are primarily used to determine the activity of the alternative pathway of complement (APH50 titer) (Morgan, B.P. (2000; Dodds, A.W. and Sim, R.B. (1997)). Natural antibodies present in human blood to animal antigens may cause agglutination of the cells. This antibody may also cause lysis if the classical pathway is not blocked.Rabbit erythrocytes are attacked and lysed by the alternative pathways of most mammalian species. It has not been clearly demonstrated why rabbit complement does not lyse rabbit Er when most other animal species do lyse these cells, although they do carry rabbit DAF which works on rabbit, but not human complement enzymes.RegulationRabbit erythrocytes (Er) are used for human complement assays partly for convenience, but also because they lack membrane-bound regulators of human complement. No significant level of functional DAF, CD59 or CR1 exists on Er for human complement. Thus, Er are useful for their lack of membrane regulatory activities... Read More | Aprotinin is a competitive serine protease inhibitor that inhibits trypsin,chymotrypsin,kallikrein and plasmin.Aprotinin forms stable complexes with and blocks the active sites of enzymes. Binding is reversible with most aprotinin,protease complexes and dissociating at pH >10 or <3. Effective Aprotinin is a competitive serine protease inhibitor that inhibits trypsin,chymotrypsin,kallikrein and plasmin.Aprotinin forms stable complexes with and blocks the active sites of enzymes. Binding is reversible with most aprotinin,protease complexes and dissociating at pH >10 or <3. Effective concentration is equimolar with protease.Recombinant aprotinin is expressed in E. Coli, and purified with HPLC. It contains no animal-derived components. This is a recombinant form of bovine lung aprotinin, which is traditionally isolated from bovine lung by methods involving fractional precipitation, gel filtration, and ion exchange chromatography. UNIT DEFINITION:A conversion factor for Aprotinin is: 1 EPU = 1 USP Aprotinin Unit = 1800 KIU... Read More | Purity> 95% by SDS-PAGE and HPLC analyses.FunctionGrowth factor that controls proliferation and cellular differentiation in the retina and bone formation. Plays a key role in regulating apoptosis during retinal development. Establishes dorsal-ventral positional information in the retina and Purity> 95% by SDS-PAGE and HPLC analyses.FunctionGrowth factor that controls proliferation and cellular differentiation in the retina and bone formation. Plays a key role in regulating apoptosis during retinal development. Establishes dorsal-ventral positional information in the retina and controls the formation of the retinotectal map (PubMed:23307924). Required for normal formation of bones and joints in the limbs, skull, digits and axial skeleton. Plays a key role in establishing boundaries between skeletal elements during development. Regulation of GDF6 expression seems to be a mechanism for evolving species-specific changes in skeletal strucutres. Seems to positively regulates differentiation of chondrogenic tissue through the growth factor receptors subunits BMPR1A, BMPR1B, BMPR2 and ACVR2A, leading to the activation of SMAD1-SMAD5-SMAD8 complex. The regulation of chondrogenic differentiation is inhibited by NOG (PubMed:26643732). Also involved in the induction of adipogenesis from mesenchymal stem cells. This mechanism acts through the growth factor receptors subunits BMPR1A, BMPR2 and ACVR2A and the activation of SMAD1-SMAD5-SMAD8 complex and MAPK14/p38... Read More | Purity: >90%, by SDS-PAGE visualized with Coomassie® Blue Staining. Description: Major histocompatibility complex, class II, DR alpha (HLA-DRA) belongs to the MHC class II family. HLA-DRA binds peptides derived from antigens which access the endocytic route of antigen presenting cells (APC) Purity: >90%, by SDS-PAGE visualized with Coomassie® Blue Staining. Description: Major histocompatibility complex, class II, DR alpha (HLA-DRA) belongs to the MHC class II family. HLA-DRA binds peptides derived from antigens which access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for identification by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mainly by degradation of proteins which access the endocytic route, where they are processed by lysosomal proteases and other hydrolases... Read More | Purity>95% SDS-PAGE.FunctionCytokine that binds to TNFRSF10A/TRAILR1, TNFRSF10B/TRAILR2, TNFRSF10C/TRAILR3, TNFRSF10D/TRAILR4 and possibly also to TNFRSF11B/OPG. Induces apoptosis. Its activity may be modulated by binding to the decoy receptors TNFRSF10C/TRAILR3, TNFRSF10D/TRAILR4 and TNFRSF11B/Purity>95% SDS-PAGE.FunctionCytokine that binds to TNFRSF10A/TRAILR1, TNFRSF10B/TRAILR2, TNFRSF10C/TRAILR3, TNFRSF10D/TRAILR4 and possibly also to TNFRSF11B/OPG. Induces apoptosis. Its activity may be modulated by binding to the decoy receptors TNFRSF10C/TRAILR3, TNFRSF10D/TRAILR4 and TNFRSF11B/OPG that cannot induce apoptosis... Read More |