Enables Hsp70 protein binding activity. Predicted to be involved in regulation of bone mineralization. Predicted to act upstream of or within extracellular matrix organization; positive regulation of cell-substrate adhesion; and regulation of enamel mineralization. Located in extracellular matrix. Orthologous to human DMP1 (dentin matrix acidic phosphoprotein 1). [provided by Alliance of Genome Resources, Apr 2022]