CD97 antigen; Leukocyte antigen CD97; CD97; contains CD97 antigen subunit alpha & CD97 antigen subunit beta (CD97)

Function

• receptor potentially involved in both adhesion & signaling processes early after leukocyte activation
• role in leukocyte migration (putative)
• interacts with complement decay-accelerating factor (DAF)
• the largest isoform (isoform 1) interacts with chondroitin sulfate
• proteolytically cleaved into 2 subunits, an extracellular alpha subunit & a seven-transmembrane subunit (putative)
• binds to CD55

Structure

• forms a heterodimer, consisting of a large extracellular region (alpha subunit) non-covalently linked to a seven- transmembrane moiety (beta subunit).
• the first 2 EGF domains mediate the interaction with DAF
• a 3rd tandemly arranged EGF domain is necessary for the structural integrity of the binding region
• binding to chondroitin sulfate is mediated by the 4th EGF domain
• belongs to the G-protein coupled receptor 2 family LN-TM7 subfamily
• contains 5 EGF-like domains
• contains 1 GPS domain

Compartment

• cell membrane
• CD97 antigen subunit alpha: secreted

Alternative splicing

named isoforms=3

Expression

• broadly expressed
• present on the surface of most activated leukocytes
• rapid up-regulation during lymphocyte activation
• found on most hematopoietic cells, including
  • activated lymphocytes, activated T > B cells
  • monocytes, macrophages,
  • dendritic cells
  • granulocytes
  • smooth muscle cells
• increased expression of CD97 in the synovium is accompanied by detectable levels of soluble CD97 in the synovial fluid
• microglia stain negatively with antibody

Pathology

• CD97 is expressed in some carcinomas
  • thyroid carcinomas
  • GI adenocarcinomas
    • colorectal carcinoma
    • gastric cancer
    • esophageal cancer
    • pancreatic cancer
• expressed in sites of inflammation in skin, lung, brain, joints
• expression is increased under inflammatory conditions in the CNS of multiple sclerosis & in synovial tissue of patients with rheumatoid arthritis

More general terms

• CD antigen
• G-protein coupled receptor; serpentine receptor
• glycoprotein

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:976
• OMIM: https://mirror.omim.org/entry/601211
• UniProt: http://www.uniprot.org/uniprot/P48960.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=976