Recombinant Mouse DSPG3 Protein, CF

DSPG3 (dermatan sulfate proteoglycan 3), also called epiphycan (gene name EPYC) or PG-Lb, is a 95 ‑ 100 kDa class III subfamily member of the SLRP (small leucine-rich proteoglycans) family of molecules (1 ‑ 4). It is synthesized as a 322 amino acid (aa) precursor that contains a 19 aa signal sequence and a 303 aa mature region. The mature molecule contains three N-terminal O-glycosylation sites (including one found to bind dermatin sulfate) and a glutamic acid-rich motif followed by six leucine-rich repeats (LRR) that contain two potential N-glycosylation sites (2, 3). The LRR are flanked by two intrachain disulfide bonds (5). Class III SLRPs, including DSPG3, Osteoglycin and Opticin, contain 6 ‑ 7 LRR, while other classes contain 8 ‑ 10 LRR (1, 4). Collagen binding maps to the LRR (1). Mature mouse DSPG3 shares 97%, 85%, 84%, and 83% aa sequence identity with rat, human, canine and bovine DSPG3, respectively. DSPG3 is found predominantly in epiphyseal cartilage, although DSPG3 mRNA is also detected in mouse testis and human ligament and placenta (2‑4). In mouse, expression begins in mid-gestation as an intermediate marker for chondrogenesis, peaks at birth and declines thereafter (6, 7). Deletion of DSPG3 in mouse results in a mild postnatal phenotype that worsens synergistically when the co‑expressed SLRP biglycan is also deleted (7). The double-mutant phenotype includes premature osteoarthritis, indicating a role for DSPG3, in cooperation with other SLRPs, in stability of the collagen matrix and maintenance of joint integrity (7).