receptor-binding cancer antigen expressed on SiSo cells; cancer-associated surface antigen RCAS1; estrogen receptor-binding fragment-associated gene 9 protein (EBAG9, RCAS1)

Function

• may participate in suppression of cell proliferation
• induces apoptotic cell death through activation of IL-1-beta converting enzyme (ICE)-like proteases

Structure

• homodimer
• the coiled coil domain is necessary for homodimerization

Compartment

• Golgi apparatus membrane
• single-pass type 3 membrane protein
• may exist as a soluble form which has the same biological activities

Expression

• widely expressed
• expressed in ovary, testis, prostate, thymus, muscle & heart
• not expressed in small intestine, colon, lymph nodes, or peripherical blood lymphocytes
• induced by estrogen

Pathology

• may serve as a prognostic marker for cancers such as adenocarcinoma of the lung & breast cancers
• present & overexpressed in many patients suffering from breast carcinomas; expression correlates with tumor grade, suggesting that it may be involved in cancer immune escape
• not directly a tumor-associated antigen, but it rather modulates surface expression of tumor-associated O-linked glycan Tn when it is overexpressed, suggesting that it contributes indirectly to the antigenicity of tumor cells

Notes

• initially reported to be a ligand for some putative receptor present on T-cells, B-cells, NK cells & various human cell lines; however, it does not bind any receptor [4

More general terms

• plasma membrane protein
• phosphoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=9166
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:9166
• OMIM: https://mirror.omim.org/entry/605772
• UniProt: http://www.uniprot.org/uniprot/O00559.html