Secondary Structure Predictions for Rat Osteopontin

Five computerized methods were used to predict the secondary structure of osteopontin - a bone-derived cell attachment protein. The amino terminal one-fifth and the carboxy terminal one-third of the 301 amino acid protein contain eight alpha helices (41% of the total residues). The middle of the molecule contains a very acidic region of no predicted structure followed by two segments of beta structure which flank the cell attachment site of osteopontin. Examination of the amino acid sequence also revealed a potential calcium binding loop and two potential heparin binding sites.