Enables glycosaminoglycan binding activity. Acts upstream of or within peptide cross-linking via chondroitin 4-sulfate glycosaminoglycan. Predicted to be located in extracellular matrix and extracellular space. Is expressed in central nervous system and retina. Orthologous to human SPOCK3 (SPARC (osteonectin), cwcv and kazal like domains proteoglycan 3). [provided by Alliance of Genome Resources, Apr 2022]