β-Actin (13E5) Rabbit mAb (Alexa Fluor® 555 Conjugate)
What is a Recombinant Antibody and Why is it Important?
Recombinant antibodies offer several key advantages compared to traditional antibodies.
These include superior lot-to-lot consistency, continuous supply, and animal-free manufacturing.
As such, recombinant antibodies are seeing increased use for scientific research, especially as a means of
addressing the ongoing reproducibility crisis.
What is a Recombinant Antibody?
Traditional polyclonal and monoclonal antibodies are the product of normal B cell development and genetic recombination.
They are generated by immunizing an animal with an antigen to elicit an immune response. While polyclonal antibodies are
secreted by many different B cell clones and recognize multiple antigenic epitopes, monoclonals originate from a single B
cell clone and are specific for just one epitope.
Recombinant antibodies are monoclonal, but their production involves in vitro genetic manipulation.
After cloning the antibody genes into an expression vector, this is then transfected into an appropriate host cell line
for antibody expression. Mammalian cell lines are most commonly used for recombinant antibody production, although cell
lines of bacterial, yeast, or insect origin are also suitable.
Superior Lot-to-Lot Consistency
Because recombinant antibody production involves sequencing the antibody light and heavy chains, it is a highly controlled
and reliable process. In contrast, hybridoma-based systems for producing monoclonal antibodies are subject to genetic
drift and instability, increasing the potential for lot-to-lot variability or loss of antibody expression. Recombinant
antibodies are highly consistent from lot to lot, thereby ensuring reproducible experimental results.
In vitro methods for producing antibodies are amenable to large-scale production, meaning antibody availability is
unlikely to become a limiting factor. Moreover, since the recombinant antibody sequence is known, continuity of supply
is assured; in situations where an antibody will be used to support large, long-term studies, this can be an especially
Unlike traditional methods for antibody production, recombinant approaches avoid the need to use animals.
Where polyclonal antibodies are purified directly from the serum of the immunized host, and monoclonals are purified
from either hybridoma-derived tissue culture supernatant or ascites, recombinant antibodies are instead purified from
the tissue culture supernatants of transfected host cell lines.
Regardless of whether an antibody is polyclonal, monoclonal or recombinant, it must always be properly validated
in the intended application prior to experimental use. At CST, we adhere to the
Hallmarks of Antibody Validation™,
six complementary strategies for determining the specificity, sensitivity, and functionality of an antibody in any
given assay. By carefully tailoring these strategies to each antibody product, we guarantee that CST antibodies
will work as expected, to help you achieve results you can trust.
β-Actin (13E5) Rabbit mAb (Alexa Fluor® 555 Conjugate) #8046
This Cell Signaling Technology antibody is conjugated to Alexa Fluor® 555 fluorescent dye and tested in-house for immunofluorescent analysis in monkey cells. The antibody is expected to exhibit the same species cross-reactivity as the unconjugated β-Actin (13E5) Rabbit mAb #4970.
Product Usage Information
Supplied in PBS (pH 7.2), less than 0.1% sodium azide and 2 mg/ml BSA. Store at 4°C. Do not aliquot the antibody. Protect from light. Do not freeze.
NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalently purified water.
20X Phosphate Buffered Saline (PBS): (9808) To prepare 1L 1X PBS: add 50 ml 20X PBS to 950 ml dH2O, mix. Adjust pH to 8.0.
Formaldehyde: 16%, methanol free, Polysciences, Inc. (cat# 18814), use fresh and store opened vials at 4°C in dark, dilute in 1X PBS for use.
Blocking Buffer (1X PBS / 5% normal goat serum (#5425) / 0.3% Triton™ X-100): To prepare 10 ml: add 0.5 ml normal goat serum and 0.5 ml 20X PBS to 9.0 ml dH2O, mix. While stirring, add 30 µl Triton™ X-100.
Antibody Dilution Buffer (1X PBS / 1% BSA / 0.3% Triton X-100): To prepare 10 ml, add 30 µl Triton™ X-100 to 10 ml 1X PBS. Mix well then add 0.1 g BSA (9998), mix.
B. Specimen Preparation - Cultured Cell Lines (IF-IC)
NOTE: Cells should be grown, treated, fixed and stained directly in multiwell plates, chamber slides or on coverslips.
Aspirate liquid, then cover cells to a depth of 2–3 mm with 4% formaldehyde in 1X PBS. NOTE: Formaldehyde is toxic, use only in fume hood.
Allow cells to fix for 15 minutes at room temperature.
Aspirate fixative, rinse three times in 1X PBS for 5 minutes each.
Proceed with Immunostaining (Section C).
NOTE: All subsequent incubations should be carried out at room temperature unless otherwise noted in a humid light-tight box or covered dish/plate to prevent drying and fluorochrome fading.
Methanol Permeabilization Step: Cover cells with ice-cold 100% methanol (use enough to cover completely to a depth of 3–5 mm, DO NOT LET DRY), incubate in methanol for 10 minutes at –20°C, rinse in 1X PBS for 5 minutes.
Block specimen in Blocking Buffer for 60 minutes.
While blocking, prepare primary antibody by diluting as indicated on product webpage in Antibody Dilution Buffer.
Coverslip slides with Prolong® Gold Antifade Reagent (#9071), Prolong® Gold AntiFade Reagent with DAPI (#8961).
For best results examine specimens immediately using appropriate excitation wavelength. For long term storage, store slides flat at 4°C protected from light.
posted November 2006
revised December 2010
Protocol Id: 220
Specificity / Sensitivity
β-Actin (13E5) Rabbit mAb (Alexa Fluor® 555 Conjugate) detects endogenous levels of total β-actin protein. Depsite the high sequence identity between the cytoplasmic actin isoforms, β-actin and cytoplasmic γ-actin, β-Actin (13E5) Rabbit mAb (Alexa Fluor® 555 Conjugate) #8046 does not cross-react with cytoplasmic γ-actin, or any other actin isoforms.
Human, Mouse, Rat, Monkey, Bovine, Pig
Species predicted to react based on 100% sequence homology:
The antigen sequence used to produce this antibody shares
100% sequence homology with the species listed here, but
reactivity has not been tested or confirmed to work by CST.
Use of this product with these species is not covered under
Antibody Performance Guarantee.
Hamster, Chicken, Dog, Horse, Rabbit
Source / Purification
Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues near the amino-terminus of human β-actin protein.
Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are ubiquitously expressed, controlling cell structure and motility (1). While all actin isoforms are highly homologous, cytoplasmic β- and γ-actin protein sequences differ by only four biochemically similar amino acids (2). For this reason, antibodies raised to β-actin may cross-react with γ-actin, and vice versa. α-cardiac and α-skeletal actin are expressed in striated cardiac and skeletal muscles, respectively; two smooth muscle actins, α- and γ-actin, are found primarily in vascular smooth muscle and enteric smooth muscle, respectively. These actin isoforms regulate the contractile potential of muscle cells (1). Actin exists mainly as a fibrous polymer, F-actin. In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (3). The ARP2/3 complex stabilizes F-actin fragments and promotes formation of new actin filaments (3). Research studies have shown that actin is hyperphosphorylated in primary breast tumors (4). Cleavage of actin under apoptotic conditions has been observed in vitro and in cardiac and skeletal muscle, as shown in research studies (5-7). Actin cleavage by caspase-3 may accelerate ubiquitin/proteasome-dependent muscle proteolysis (7).
For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology is a trademark of Cell Signaling Technology, Inc.
This product is provided under an intellectual property license from Life Technologies Corporation. The transfer of this product is conditioned on the buyer using the purchased product solely in research conducted by the buyer, excluding contract research or any fee for service research, and the buyer must not (1) use this product or its components for (a) diagnostic, therapeutic or prophylactic purposes; (b) testing, analysis or screening services, or information in return for compensation on a per-test basis; or (c) manufacturing or quality assurance or quality control, and/or (2) sell or transfer this product or its components for resale, whether or not resold for use in research. For information on purchasing a license to this product for purposes other than as described above, contact Life Technologies Corporation, 5791 Van Allen Way, Carlsbad, CA 92008 USA or [email protected]