IBSP
Developmental stage
In fetal developing bone of gestational age of 14-17 weeks, expressed in mature osteoblasts, young osteocytes and osteoclasts (at protein level) (PubMed:1818768). Expressed in bone matrix (at protein level) (PubMed:1818768). Expressed in osteoid at the borderline with mature mineralized matrix (at protein level) (PubMed:1818768). Expressed in chondrocytes in the growth plate (at protein level) (PubMed:1818768). Not detected in preosteogenic cells in the inner layer of the periosteum and in the fibroblastic cells in the outer layer (at protein level) (PubMed:1818768). Not detected in cartilage matrix (at protein level) (PubMed:1818768). Not detected in ocular tissues, skin, tendon, muscle and kidney of gestational age of 14-17 weeks (at protein level) (PubMed:1818768).
Domain
The Arg-Gly-Asp (RGD) sequence serves as an integrin-binding motif and is required for integrin-mediated cell attachment.
Function
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).
Post-translational modifications
N-glycosylated; glycans consist of sialylated and core-fucosylated bi-, tri- and tetraantennary chains.
O-glycosylated at eight sites; mucin-type glycans contain Gal, GlcNAc, GalNAc and terminal NeuAc.
Tissue Specificity
Expressed in bone (at protein level) (PubMed:11459848). Expressed in trophoblast cells of placenta (at protein level) (PubMed:1818768). Expressed in brain (PubMed:36261010).
Cellular localization
- Secreted
Alternative names
BNSP, IBSP, Integrin-binding sialoprotein, Bone sialoprotein 2, Bone sialoprotein II, Cell-binding sialoprotein, BSP II