Enables transforming growth factor beta binding activity. Involved in several processes, including cholesterol efflux; cholesterol homeostasis; and nervous system development. Acts upstream of or within several processes, including ciliary body morphogenesis; negative regulation of Wnt signaling pathway; and telencephalon development. Located in extracellular space. Is expressed in embryo and olfactory epithelium. Orthologous to human TSKU (tsukushi, small leucine rich proteoglycan). [provided by Alliance of Genome Resources, Apr 2022]