Mouse Osteoadherin/OSAD Alexa Fluor® 488-conjugated Antibody

Osteoadherin (OSAD), also known as Osteomodulin, is an extracellular matrix keratan sulfate proteoglycan that belongs to the class II subfamily of small leucine-rich proteoglycans (SLRP). LRR motifs consist of approximately 20‑30 amino acids (aa) with conserved leucine spacing, folded into a structure with one beta-sheet and one alpha-helix (1, 2). The mouse OSAD cDNA encodes a 423 aa precursor that contains a 20 aa signal sequence and twelve tandem leucine rich repeats (3). Mouse OSAD shares 75%, 79%, and 91% aa sequence identity with bovine, human, and rat OSAD, respectively. Mouse OSAD shares 32‑35% aa sequence identity with mouse class II SLRPs Fibromodulin, Keratocan, Lumican, and PRELP. Bovine, mouse, and rat OSAD are expressed as 60‑85 kDa molecules, even though the amino acid sequence for each predicts a size of 46‑47 kDa. The primary difference is due to the presence of extensive N-linked glycosylation that can vary between tissues of the same species (4, 5). Human OSAD is expressed as an even larger 110 kDa molecule in teeth (6). OSAD contains eight sulfated tyrosine residues (4, 7) and is distinguished from other class II SLRPs by the presence of an approximately 70 aa C‑terminal acidic domain (3). OSAD is expressed by fetal and adult osteoblasts but is not detectable in cartilage or tendon (3, 4, 8). In dental tissue, OSAD is expressed by odontoblasts and ameloblasts (5, 9‑11) and is involved in the mineralization of bone and teeth (5, 11,12). OSAD promotes the adhesion of osteoblasts and odontoblasts to the surrounding matrix, an interaction that is mediated by Integrin alpha_V beta₃ (4, 6).