Description
IBSP (integrin-binding sialoprotein; also BSP or bone sialoprotein (II)) is a 55-75 kD, secreted, variably glycosylated, monomeric noncollagenous member of the SIBLING family of extracellular matrix (ECM) proteins (1-3). It is principally associated with the early stages of bone mineralization. BSP is synthesized as a 317 amino acid (aa) precursor that contains a 16 aa signal sequence and a 301 aa mature region (4-6). BSP is highly glycosylated, sulfated, and phosphorylated. Phosphorylation may impact HAp growth, while carbohydrate may regulate cell adhesion (1, 3, 13). Mature human BSP is 70%, 72%, 78%, and 72% aa identical to porcine, rat, canine, and mouse BSP, respectively. BSP is synthesized by megakaryocytes/ platelets, osteoblasts, osteocytes, odontoblasts, osteoclasts, and bone marrow stromal cells (14-17).
Recombinant human BSP is composed of a Human CD33 Signal Peptide (Met 1-Arg 399), followed by Human IBSP (Phe 17-Gln 317) (Accession #AAC95490), and with a poly-his tag at the C-terminus