A TGF-β-family signal sharing myostatin's receptors, with broader roles. Structurally it is TGF-β superfamily dimer (βA–βA).

How strong is the evidence for Activin A?

PeptideHormone grades Activin A at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.

What is the half-life of Activin A?

The reported circulating half-life of Activin A is Short; set by follistatin binding.

Activin A

A TGF-β-family signal sharing myostatin's receptors, with broader roles.

EndogenousEstablished

Shares myostatin's receptors and much else besides — which is precisely why blocking this pathway is harder than it first appears.

Identity

Class: TGF-β superfamily dimer (βA–βA)
Source: Many tissues (gonads, muscle, immune cells)
Receptor: Activin type II receptors (ActRIIA/B) → Smad2/3

Key properties

Evidence floorPreclinicalREF1PRE1

Molecular weight

≈ 26,000 Da

REF

Half-life (native)

Short; set by follistatin binding

PRE

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

Activin A signals through the same activin type II receptors as myostatin, contributing to muscle wasting, fibrosis, inflammation, and reproductive signaling depending on context. Its overlap with myostatin is why receptor-level blockade affects both.

Reference notes

Activin A and myostatin converge on the same activin type II receptors.
It has wide-ranging roles beyond muscle, including in reproduction and fibrosis.
Receptor-level (ActRII) blockade affects activin and myostatin together.

Common questions

What is Activin A?: A TGF-β-family signal sharing myostatin's receptors, with broader roles. Structurally it is TGF-β superfamily dimer (βA–βA).
How does Activin A work?: Activin A signals through the same activin type II receptors as myostatin, contributing to muscle wasting, fibrosis, inflammation, and reproductive signaling depending on context. Its overlap with myostatin is why receptor-level blockade affects both.
How strong is the evidence for Activin A?: PeptideHormone grades Activin A at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of Activin A?: The reported circulating half-life of Activin A is Short; set by follistatin binding.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

1.Principles of the activin receptor signaling pathway and its inhibition · Cytokine & growth factor reviews, 2021 · PMID 33933900
2.Myostatin/Activin Receptor Ligands in Muscle and the Development Status of Attenuating Drugs · Endocrine reviews, 2022 · PMID 34520530

External references

Activin A in the public knowledge graph — the same entity resolved across the authoritative chemistry and protein databases.