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Monoclonal Anti-Actin, α-Smooth Muscle

clone 1A4, ascites fluid

Anti-Alpha Smooth Muscle Actin Antibody, SMA, Alpha Smooth Muscle Actin Antibody - Monoclonal Anti-Actin, α-Smooth Muscle, Alpha Smooth Muscle Actin Antibody Sigma

Quality Level

biological source




antibody form

ascites fluid

antibody product type

primary antibodies


1A4, monoclonal

mol wt

antigen ~42 kDa


15 mM sodium azide

species reactivity

human, frog, sheep, chicken, goat, bovine, rat, guinea pig, mouse, canine, rabbit, snake


immunohistochemistry (formalin-fixed, paraffin-embedded sections): suitable using smooth muscle cells
immunohistochemistry (frozen sections): suitable using smooth muscle cells
indirect immunofluorescence: 1:400 using blood vessels in sections of human appendix
western blot: suitable using smooth muscle cells



UniProt accession no.


research pathology

shipped in

dry ice

storage temp.


Gene Information

human ... ACTA2(59)
mouse ... Acta2(11475)
rat ... Acta2(81633)

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General description

The antibody (also known as anti-α-Sm-1) is specific for the single isoform of α-smooth muscle actin. It reacts specifically with α-smooth muscle actin in immunoblotting assays and labels smooth muscle cells in frozen or formalin-fixed, paraffin-embedded tissue sections.
Actins are cytoskeletal proteins that regulate cell motility. Several scaffolding, signaling and actin-binding proteins regulate the interconversions between filamentous F-actins and monomeric G-actins. Cellular actins of various species have very similar immunological and physical properties. Hence, the use of monoclonal antibody to actin provides a specific and useful tool for studying the localization, structure and function of actin proteins. Actin 2 (ACTA2), the smooth muscle actin is encoded on human chromosome 10q23.31.
Mouse monoclonal anti-actin, α-smooth muscle antibody binds to actin from human, mouse, rat, bovine, chicken, frog, goat, guinea pig, rabbit, dog, sheep, and snake.
Monoclonal Anti-α Smooth Muscle Actin (mouse IgG2a isotype) is derived from the hybridoma produced by the fusion of mouse myeloma cells and splenocytes from an immunized mouse. The NH2 terminal synthetic decapeptide of α-smooth muscle actin coupled to keyhole limpet hemocyanin (KLH) was used as the immunogen. The isotype is determined using Sigma ImmunoTypeTM Kit (Sigma Stock No. ISO-1) and by a double diffusion immunoassay using Mouse Monoclonal Antibody Isotyping Reagents (Sigma Stock No. ISO-2).


Monoclonal Anti-α Smooth Muscle Actin is specific for the single isoform α-actin. It reacts specifically with a smooth muscle actin using immunoblotting and indirect immunofluorescent labeling of formalin-fixed, paraffin embedded or frozen tissue sections. The antibody can be used for immunocytochemical localization of the α smooth muscle actin by means of immunoperoxidase, immunofluorescent, ELISA or immunoblot techniques. The antibody reacts with human, mouse, rat, bovine, chicken, frog, goat, guinea pig, rabbit, dog, sheep, and snake.


N-terminal synthetic decapeptide of α-smooth muscle actin.


Paraffin embedded sections of rat testis tissue grafts were immunohistochemically stained with mouse monoclonal anti-smooth muscle actin.
IHC analysis of x-gal stained muouse cardiac tissue was performed using the primary antibody, mouse monoclonal anti-smooth muscle actin to identify myofibroblasts.
Mouse monoclonal anti-actin, α-smooth muscle antibody has been used for western blot assays using whole kidney homogenates in human anaplastic thyroid cancer cells. The product has also been used for immunohistochemical assays using mice tissue sections in liver sections and uterine sections.
Monoclonal Anti-Actin, α-Smooth Muscle antibody has been used in the detection of actin 2 in breast fibroblasts using immunofluorescence staining.
Immunocytochemistry was performed on smooth muscle cells from bovine aortas using the monoclonal anti-ACTA2 antibody. Cells were first grown on glass cover slips and fixed in 50% acetone/EtOH for 10 minutes at 4 degrees.

Biochem/physiol Actions

Actin is one of the most conserved eukaryotic proteins, it is expressed in mammals and birds as six isoforms characterized by electrophoresis and amino acid sequence analysis. Four of the six represent differentiation markers of muscle tissues. Actin isoforms show >90% overall sequence homology, but only 50-60% homology in their 18 NH2-terminal residues. The NH2-terminal region of actin appears to be a major antigenic region, and may be involved in the interaction of actin with other proteins such as myosin. It has been shown that the relative proportion of actin isoforms are different in smooth muscles of different organs and change within the same population of smooth muscle cells during development, pathological situations and different culture conditions.
Mutations in actin 2 is associated with dysfunction of smooth muscles in arteries and is implicated in coronary heart disease. Mutations in ACTA2 contributes to tear and enlargement of aorta in thoracic aortic aneurysms (TAAD).

Physical form

The antibody is provided as ascites fluid containing 15mM sodium azide as a preservative.

Storage and Stability

For continuous use, store at 2-8 °C for up to one month. For extended storage, solution may be frozen in working aliquots. Repeated freezing and thawing is not recommended. If slight turbidity occurs upon prolonged storage, clarify by centrifugation before use.

Other Notes

To view an Actin antibody selection guide, please visit


Unless otherwise stated in our catalog or other company documentation accompanying the product(s), our products are intended for research use only and are not to be used for any other purpose, which includes but is not limited to, unauthorized commercial uses, in vitro diagnostic uses, ex vivo or in vivo therapeutic uses or any type of consumption or application to humans or animals.

Storage Class Code

10 - Combustible liquids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificate of Analysis

Certificate of Origin

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. What is the molecular weight of actin, Products  A2066 and A2547?

    Actin has a molecular weight of 42 kDa.

  3. Why do I have 3 bands on my western blot when using Product A2547, Monoclonal Anti-Actin, α-Smooth Muscle antibody produced in mouse?

    While actin should run as a 42 kDa band when detected by Western blotting, there are recent observations that cleavage products can be seen in cells undergoing apoptosis. Initial cleavage gives a band at 41 kDa, which may appear as a doublet on the blot. In addition, further cleavage results in a major band at 30 kDa and a small band at 14 kDa which have been shown to be cleavage products due to the action of interleukin 1 -converting enzyme. This may explain the detection of smaller bands when blotting with this antibody. This banding pattern may be detected with other actin antibodies as well. Kayalar, C., et al., Proc. Natl. Acad. Sci., USA, 93:2234-2238, (1996).

  4. What is the antibody concentration of Product A2547, Monoclonal Anti-Actin, α-Smooth Muscle antibody produced in mouse?

    This antibody is ascities fluid.  The amount of protein present and the amount of IgG1 present is indicated on the Lot-specific Certificate of Analysis.

  5. Is there a protocol for using Product A2547, Monoclonal Anti-Actin, α-Smooth Muscle antibody produced in mouse, in immunohistochemistry?

    This antibody is used in our Immunohistochemistry Kit, Product No. IMMH2.

  6. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  7. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  8. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  9. Can Product A2547,  Monoclonal Anti-Actin, α-Smooth Muscle antibody detect beta actin?

    No, Product A2547,  Monoclonal Anti-Actin, α-Smooth Muscle antibody will not cross react with beta actin. 

  10. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

Germán Cuesto et al.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 31(8), 2721-2733 (2011-03-19)
The possibility of changing the number of synapses may be an important asset in the treatment of neurological diseases. In this context, the synaptogenic role of the phosphoinositide-3-kinase (PI3K) signaling cascade has been previously demonstrated in Drosophila. This study shows
Mutations in smooth muscle alpha-actin (ACTA2) cause coronary artery disease, stroke, and Moyamoya disease, along with thoracic aortic disease.
Guo DC, et al.
American Journal of Human Genetics, 84(5), 617-627 (2009)
Thrombospondin-1 Silencing Down-Regulates Integrin Expression Levels in Human Anaplastic Thyroid Cancer Cells with BRAFV600E: New Insights in the Host Tissue Adaptation and Homeostasis of Tumor Microenvironment.
Duquette M, et al.
Frontiers in Endocrinology, 4, 189-189 null
Nikolaus Kneidinger et al.
American journal of respiratory and critical care medicine, 183(6), 723-733 (2010-10-05)
Chronic obstructive pulmonary disease (COPD) is a devastating disease, for which no causal therapy is available. To characterize WNT/β-catenin signaling in COPD in humans and elucidate its potential role as a preventive and therapeutic target in experimental emphysema in mice.
Thoracic aortic aneurysm (TAAD)-causing mutation in actin affects formin regulation of polymerization.
Malloy LE, et al.
The Journal of Biological Chemistry, 287(34), 28398-28408 (2012)

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