CD97 is a member of the LNB-TM7 protein family, which is a subfamily of the G-protein coupled receptor 2 family (1-3). Molecules in this family have EGF-like modules coupled to class B G-protein 7-transmembrane (TM) domains by a glycosylated (mucin) stalk. Three isoforms of CD97 are produced by alternative splicing in mouse. Isoform 1, which is the longest, contains four EGF-like domains. Only the N-terminal EGF-like domain does not bind calcium. In isoform 2, which is described in this insert, does not contain this sequence that corresponds to aa 120- 213 in isoform 1. Compared to isoform 1, isoform 3 lacks a 45aa sequence between EGF-like domains 2 and 3 (4, 5). Cells known to express CD97 include monocytes, macrophages, T cells, select B cells, dendritic cells and, potentially, vascular and visceral smooth muscle cells (1, 6-7). CD97 is also differentially expressed on murine hematopoietic stem- and progenitor-cells (7). CD55 (decay accelerating factor), a GPI-linked cell surface molecule with short consensus repeats that regulates complement activation on cell surfaces, chondroiten sulfate and the integrin alpha 5 beta (also known as VLA-5) have been identified as cellular ligands for CD97 (7). The composition of the EGF domain region defines the ligand specificity of the different CD97 isoforms (7). The first and second EGF domains interact with CD55, whereas the fourth EGF domain binds chondroitin sulfate (7). The ligand affinity of the CD97 isoforms differs (7). While affinity for CD55 is significantly higher for the smaller isoforms, chondroitin sulfate interacts exclusively with the largest isoforms (7). It has been demonstrated that CD97 is required for neutrophil migration and host defense (8). Source: A DNA sequence encoding the EGF-like regions of the extracellular domain of the isoform 2 mouse CD97 (Met 1-His 384, AAH06676) was fused with a 6X histidine tag at the C-terminus and expressed in a Chinese Hamster Ovary cells. Molecular Mass: The N-terminal aa sequencing of the recombinant mouse CD97v2 was blocked, which is consistent with the predicted Gln 24 as the first aa. The recombinant mouse CD97v2 has a predicted molecular mass of approximately 40.6kD and migrates as an approximately 55-65kD protein in SDS-PAGE under reducing conditions. Activity: Measured by its ability to bind rmCD55 in a functional ELISA type binding assay. When rmCD55 is immobilized at 0.5ug/ml, 100ul/well, the concentration of rmCD97 that produces 50% of the optimal binding response is found to be approximately 0.15-0.5uml. Endotoxin: 1.0 EU/1ug (LAL) Storage and Stability: 12 months from date of receipt, 20 to 70C as supplied. 1 month, 2 to 8C under sterile conditions after reconstitution. 3 months, 20 to 70C under sterile conditions after reconstitution. Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
