Binds tightly to hydroxyapatite (PubMed:11459848). Appears to form an integral part of the mineralized matrix (PubMed:1818768). Probably important to cell-matrix interaction (PubMed:1818768). Promotes adhesion and migration of various cells via the alpha-V/beta-3 integrin receptor (ITGAV:ITGB3) (PubMed:10640428, PubMed:11459848, PubMed:24103036). {ECO:0000269|PubMed:10640428, ECO:0000269|PubMed:11459848, ECO:0000269|PubMed:1818768, ECO:0000269|PubMed:24103036}. This is the function of IBSP (integrin binding sialoprotein, Ensembl gene identifier ENSG00000029559).