| IBSP (integrinbinding sialoprotein, also BSP or bone sialoprotein II) is a 5575kD, secreted, variably glycosylated, monomeric noncollagenous member of the SIBLING family of extracellular matrix (ECM) proteins. It is principally associated with the early stages of bone mineralization. Mouse BSP is synthesized as a 324aa precursor that contains a 16aa signal sequence and a 308aa mature region. The mature segment is divided into a basic Nterminus (aa17-62), a central region (aa63233), and an acidic Cterminus (aa234317). Functional segments associated with the mature molecule include a type I collagen binding domain (aa1946), two nonRGD cell binding sites (aa3057 and 261281), an RGD alpha-v-b-3 integrinbinding site (aa286288) and two regions that are potential hydroxyapatite (HAp) nucleation domains (aa7683 and 151158). HAp formation requires a BSP nucleation site composed of at least eight consecutive glutamic acid residues and, likely, a contribution from a BSPassociated conucleator BSP is highly glycosylated, sulfated and phosphorylated. Phosphorylation promotes HAp nucleation, while carbohydrate may regulate cell adhesion. Interaction with integrins stimulates cell migration and survival, and has been implicated in bone metastasis of cancers, especially those of breast and prostate. Mature mouse BSP shares 90 identity with rat, 70% with human, 67% with canine, equine and porcine, and 64% with bovine BSP, respectively. BSP is synthesized by megakaryocytes/platelets, osteoblasts, osteocytes, odontoblasts, osteoclasts and bone marrow stromal cells. Source: Chinese Hamster Ovary cell line, CHO-derived Met1-Gln324, with a C-terminal 6His tag. SDS-PAGE: 70-90kD, reducing conditions Activity: Measured by the ability of the immobilized protein to support the adhesion of the MCF-7 human breast adenocarcinoma cells. When 5x10e4 cells/well are added to recombinant mouse IBSP coated plates (3ug/ml with 100ul/well), approximately 60-80% will adhere after 30 minutes at 37 C. Endotoxin Level: 1EU/1ug (LAL) Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile PBS, 0.02% sodium azide. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
