Source comparison
Receptor and signalling pathway comparison
TB-500 does not signal through a canonical receptor-ligand binding event in the same sense as classical peptide hormones. G-actin sequestration occurs intracellularly (or at the extracellular/membrane interface via endocytosis), and ILK activation occurs downs
This comparison does not assign a generated winner or score.
- TB-500 does not signal through a canonical receptor-ligand binding event in the same sense as classical peptide hormones. G-actin sequestration occurs intracellularly (or at the extracellular/membrane interface via endocytosis), and ILK activation occurs downstream of integrin-ECM engagement rather than through a dedicated Tβ4 receptor. This has important implications for research design: TB-500 effects are cell-autonomous and do not require receptor expression profiling, but do require confirmation of ILK pathway activity (phospho-ILK, phospho-GSK-3β, nuclear β-catenin) as mechanistic evidence rather than simply measuring downstream outputs.
- Follistatin, by contrast, acts entirely extracellularly — it binds activin-A and myostatin in the extracellular space or at the cell surface before these ligands can engage their cognate receptors (ALK4/ALK5, ActRIIA/ActRIIB). Research designs studying Follistatin must therefore control for baseline myostatin and activin-A concentrations in the medium or tissue compartment being studied. Myostatin-null mice (MSTN−/−) are the definitive genetic control — Follistatin administration to MSTN−/− mice should produce a significantly attenuated CSA response, confirming that the effect is dependent on available myostatin substrate rather than some other off-target activity.
- ActRIIB-Fc (a soluble decoy receptor that also traps myostatin and activin-A, as in ACE-031) provides a mechanistic comparator for Follistatin. Because ActRIIB-Fc traps a similar but not identical ligand spectrum and does so via a different binding interface, comparing FST-315 with ActRIIB-Fc controls for “TGF-β superfamily antagonism” as a class effect, while highlighting the isoform-specific differences in BMP antagonism and ligand selectivity.