DDR-2, also known as TYR010 and TKT, is a widely expressed 130kD type I transmembrane glycoprotein belonging to the discoidin-like domain containing subfamily of receptor tyrosine kinases (1). Mature human DDR-2 consists of a 378 aa extracellular domain (ECD) that includes the discoidin-like domain, a 22 aa transmembrane segment, and a 434 aa cytoplasmic domain that includes the kinase domain (2). Within the ECD, human DDR-2 shares 53% aa sequence identity with DDR-1 and 97% aa sequence identity with mouse DDR-2. The discoidin-like domain mediates DDR-2 interactions with collagens I, III, and X (3-5). Collagens II and V are less efficacious ligands (3). DDR-2 selectively recognizes the triple helical structure of collagen compared to monomeric or denatured collagen (3, 5, 6). Within collagen II, the D2 period is required for DDR-2 binding, and the D1 period is additionally required to trigger DDR-2 autophosphorylation (6). The ECD of DDR-2 exists as a non-covalent dimer in solution, and dimerization of the receptor greatly enhances collagen binding (4, 7). DDR-2 interaction with collagen I inhibits collagen fibrillogenesis and alters collagen fiber morphology (7). Ligand binding induces DDR-2 autophosphorylation in the cytoplasmic domain (3, 5, 8), which promotes associations with Shc and Src (9). In addition to the above mechanism, DDR-2 exhibits a distinct interaction with collagen X. A region other than the discoidin-like domain of DDR-2 recognizes the non-helical NC1 domain of collagen X, and this interaction does not lead to receptor autophosphorylation (5). Activation of DDR-2 by collagen induces upregulation of MMP-1, -2, and -13 as well as DDR-2 itself (3, 8, 10). DDR-2 is implicated in collagenous matrix destruction and cell invasiveness (8, 10). DDR-2 is also upregulated in several pathological conditions, including hepatic fibrosis following injury, rheumatoid and osteoarthritis, and smooth muscle cell hyperplasia (8, 10-12).
Source:Human DDR-2 (Met 1-Arg 399) HHHHHH. A DNA sequence encoding the extracellular domain of human DDR-2 (Met 1-Arg 399; Accession # Q16832) (Karn, T., et al., 1993, Oncogene 8(12):3433) was fused with a carboxyl-terminal 6X histidine tag. The chimeric protein was expressed in a mouse myeloma cell line, NS0.
Molecular Mass:Based on N-terminal amino acid sequencing, the sequence was blocked, suggesting that the recombinant human DDR-2 may start at Gln 24. The calculated molecular mass of the mature recombinant protein is approximately 43.3 kD. As a result of glycosylation, the recombinant protein migrates as an approximately 64-65 kD protein in SDS-PAGE under reducing conditions.
Endotoxin Level:< 1.0 EU per 1 μg of the protein as determined by the LAL method.
Activity:Measured by its ability to bind collagen I (1ug/ml, 100 μL/well) in a functional ELISA with an apparent Kd < 10 nM.
Reconstitution:It is recommended that sterile PBS be added to the vial to prepare a working stock solution of no less than 100ug/ml. The carrier-free protein should be used immediately upon reconstitution to avoid losses in activity due to non-specific binding to the inside surface of the vial. For long term storage as a dilute solution, a carrier protein (e.g. 0.1% HSA or BSA) should be added to the vial.
Storage and Stability:Lyophilized samples are stable for up to twelve months at -20°C. Upon reconstitution, this protein, in the presence of a carrier protein, can be stored under sterile conditions at 2-8°C for one month or at -20°C in a manual defrost freezer for three months without detectable loss of activity. Avoid repeated freeze-thaw cycles.
