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Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein

QK035

Brand: Qkine

Follistatin-resistant activin A (FRACTA) protein has been engineered to prevent binding to the natural inhibitor, follistatin. In vivo activin A activity is regulated by follistatin, a high-affinity inhibitor; follistatin accumulates in stem cell culture, where it inhibits activin A.

Qk035 follistatin-resistant activin A (FRACTA) has equivalent bioactivity to wild-type activin A (Qk001) but does not bind follistatin so is resistant to feedback inhibition. High purity 26 kDa dimer comprising engineered mature domain of activin A protein, animal origin-free (AOF) and carrier-protein free (CF). This specialised activin A has been developed in Marko Hyvönen’s group in the University of Cambridge.

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Currency: 

Product name Catalog number Pack size Price Price (USD) Price (GBP) Price (EUR)
Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein, 25 µg QK035-0025 25 µg (select above) $ 280.00 £ 205.00 € 240.00
Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein, 50 µg QK035-0050 50 µg (select above) $ 410.00 £ 305.00 € 357.00
Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein, 100 µg QK035-0100 100 µg (select above) $ 620.00 £ 455.00 € 532.00
Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein, 500 µg QK035-0500 500 µg (select above) $ 2,500.00 £ 1,840.00 € 2,150.00
Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein, 1000 µg QK035-1000 1000 µg (select above) $ 3,950.00 £ 2,900.00 € 3,388.00

Note: prices shown do not include shipping and handling charges.

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Alternative protein names
ActA, Activin beta-A chain, Erythroid differentiation protein (EDP), Follicle-Stimulating Hormone (FSH) releasing protein (FRP), INHBA, Inhibin beta A, Inhibin beta 1
Species reactivity

human

species similarity:
mouse – 98%
rat – 98%
porcine – 98%
bovine – 98%

Frequently used together with:

Summary

  • High purity mature domain of follistatin-resistant activin A protein
  • >98%, by SDS-PAGE quantitative densitometry
  • 26 kDa (dimer)
  • Expressed in E. coli
  • Animal origin-free (AOF) and carrier protein-free.
  • Manufactured in Qkine's Cambridge, UK laboratories
  • Lyophilized from acetonitrile, TFA
  • Resuspend in 10 mM HCl at >100 µg/ml (provided with protein and free of charge), prepare single use aliquots, add carrier protein if desired and store frozen at -20°C or -80°C
Handling and Storage FAQ

Featured applications

  • Induced pluripotent and embryonic stem cell differentiation and maintenance

Bioactivity

follistatin resistant activin A Qk035 protein bioactivity lot #104287

Activin A protein activity is determined using an activin-responsive firefly luciferase reporter in HEK293T cells.  EC50 for wild-type activin A (Qk001) = 0.228 ng/ml (8.776 pM), EC50 for follistatin-resistant activin A (FRACTA, Qk035) = 0.228 ng/ml (8.792 pM).

Purity

follistatin resistant activin A FRACTA Qk035 protein purity lot #104287

FRACTA migrates as a single band at 24 kDa in non-reducing (NR) and 13 kDa as a single monomeric species upon reduction (R).  No contaminating protein bands are visible. Purified recombinant protein (1 µg) was resolved using 15% w/v SDS-PAGE in reduced (+β-mercaptothanol, R) and non-reduced conditions (NR) and stained with Coomassie Brilliant Blue R250.  Data from Qk035 lot #104287.

Further quality assays

  • Mass spectrometry: single species with expected mass
  • Analytical reversed-phase: single sharp peak
  • Endotoxin: <0.005 EU/μg protein (below level of detection)
  • Recovery from stock vial:  >95%

Protein background

Human activin A protein is a member of the TGF-β superfamily of growth factors involved in stem cell differentiation and maintenance, regulation of embryogenesis, development of the reproductive system, wound healing and regulation of immune responses.  Activin A signaling is modulated by the glycoprotein follistatin, production is which is stimulated by activin A forming a feedback loop [1], and inhibins.

Follistatin binds to and neutralises members of the TGF-β superfamily, preventing signalling by shielding the type II and I receptor binding sites [2-4].

Activins are disulfide-linked homo- and heterodimers of four inhibin β chains. The best characterized are activin A and activin B, homodimers of inhibin βA and inhibin βB respectively. Activins, like all other members in the TGF-β superfamily, are synthesized as larger precursors consisting of an N-terminal signal peptide, a pro-domain of 250–350 residues and a highly conserved mature domain. The pro-domain, which is cleaved off in the mature protein, has important roles in the biosynthesis, stabilization, transportation and signalling of the growth factors [5].

Recombinant activin A is used for maintenance of pluripotency in many human induced-pluripotent stem cell and human embryonic stem cell lines [3], and to induce stem cell differentiation into endoderm [6] and other cell fates.

Follistatin resistant activin A (FRACTA) has been developed in the lab of Marko Hyvönen at the University of Cambridge. FRACTA has been engineered to be unimpeded by follistatin while maintaining its ability to bind type I and II receptors.

negative feedback inhibition of activin A by follistatin

Background references

  1. Harrington, A. E. et al. Structural basis for the inhibition of activin signalling by follistatin. EMBO J. 25, 1035–1045 (2006). doi.org/10.1038/sj.emboj.7601000
  2. Wang, X., Fischer, G. & Hyvönen, M. Structure and activation of pro-activin A. (2016). doi:10.1038/ncomms12052
  3. Jones, K. L., Kretser, D. M. de, Patella, Shane. & Phillips, D. J. Activin A and follistatin in systemic inflammation. Molecular and Cellular Endocrinology 225, 119–125 (2004). doi.org/10.1016/j.mce.2004.07.010
  4. Walton, K. L., Makanji, Y. & Harrison, C. A. New insights into the mechanisms of activin action and inhibition. Molecular and Cellular Endocrinology 359, 2–12 (2012). doi.org/10.1016/j.mce.2011.06.030
  5. Pauklin, S. & Vallier, L. Activin/Nodal signalling in stem cells. Development 142, 607–19 (2015). doi.org/10.1242/dev.091769
  6. D’Amour, K. A. et al. Efficient differentiation of human embryonic stem cells to definitive endoderm. Nat. Biotechnol. 23, 1534–1541 (2005). doi.org/10.1038/nbt1163