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Recombinant human/mouse/rat follistatin-resistant activin A (FRACTA) protein (Qk035)
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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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 our Cambridge, UK laboratories
Lyophilized from acetonitrile, TFA
Resuspend in 10mM 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
Featured applications
Induced pluripotent and embryonic stem cell differentiation and maintenance
Bioactivity
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
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%
We are a company founded and run by scientists to provide a service and support innovation in stem cell biology and regenerative medicine. All our products are exceptionally high purity, with complete characterisation and bioactivity analysis on every lot.
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.
FAQ
Activin A is a multifunctional protein. It is involved in regulating embryonic development, cell proliferation, and differentiation. It promotes the patterning and differentiation of various organs, including the development of the mesoderm, neural, and reproductive systems. It is also involved in maintaining homeostasis, regulating immune responses, and wound healing. Finally, it stimulates the release of follicle-stimulating hormone from the pituitary gland.
Activin A is a critical factor in stem cell culture, commonly used to maintain the pluripotency of human induced pluripotent stem cells (iPSCs) and human embryonic stem cells (ESCs). It is integral to various stem cell differentiation protocols, guiding the differentiation of the definitive endoderm, neural and mesodermal lineages. Activin A is also commonly utilized in the development and maintenance of organoids.
Activin A and inhibin A are closely related proteins in the TGF-β superfamily. They share structural similarities but have distinct functions and roles in regulating various physiological processes. Activin A has broader functions beyond reproduction, which include handling embryonic development, stem cell maintenance, and the immune system. Inhibin A, conversely, is more specifically associated with the feedback control of follicle-stimulating hormones in the context of reproductive physiology.
Activin A binds to activin type I (ALK4 or ALK7) and type II (ActRIIA or ActRIIB) receptors to activate downstream SMAD signalling.
Yes, activin is involved in a feedback loop that regulates the secretion of follicle-stimulating hormone (FSH) and luteinising hormone (LH).
The activin gene family includes several genes that encode different activin subunits, forming various activin isoforms such as Inhibin Beta Subunits (INHBA / INHBB / INHBC / INHBD).
Follistatin and inhibins tightly regulate activin A activity in a feedback loop.
Our products are for research use only and not for diagnostic or therapeutic use. Products are not for resale.
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