Predicted to enable brain-derived neurotrophic factor binding activity. Predicted to be involved in cell differentiation. Predicted to act upstream of or within negative regulation of brain-derived neurotrophic factor receptor signaling pathway; negative regulation of collateral sprouting; and negative regulation of dendritic spine development. Predicted to be located in secretory granule. Orthologous to human FSTL4 (follistatin like 4). [provided by Alliance of Genome Resources, Apr 2022]