Characterization and Expression of TGF-β Proteins and Receptor in Sea Cucumber (): Insights into Potential Applications via Molecular Docking Predictions.

has long been acknowledged in traditional medicine for its therapeutic properties. The transforming growth factor-beta (TGF-β) superfamily is crucial in regulating cellular processes, including differentiation, proliferation, and immune responses. This study marks the first exploration of the gene expression localization, sequence conservation, and functional roles of TGF-β proteins, specifically activin (Activin), inhibin (Inhibin), and the TGF-β receptor (TGFBR), across various organs. In situ hybridization indicated that Activin and Inhibin are expressed in the intestine, respiratory tree, ovary, testis, and inner body wall. This suggests their roles in nutrient absorption, gas exchange, reproduction, and extracellular matrix remodeling. Notably, TGFBR demonstrated a similar tissue-specific expression pattern, except for its absence in the respiratory tree. Bioinformatics analysis reveals that TGFBR shares significant sequence similarity with TGFBR, especially in regions essential for signal transduction and inhibition. Molecular docking results indicate that Activin may promote receptor activation, while Inhibin functions as a natural antagonist, reflecting the signaling mechanisms of human TGF-β proteins. Interestingly, cross-species ternary complex docking with human TGF-β receptors further supports these findings, showing that Activin moderately engages the receptors, whereas Inhibin exhibits strong binding, suggestive of competitive inhibition. These results indicate that TGF-β proteins retain the structural and functional features of vertebrate TGF-β ligands, supporting their potential applications as natural modulators in therapeutic and functional food development.