CD275; ICOS ligand; B7 homolog 2; B7-H2; B7-like protein Gl50; B7-related protein 1; B7RP-1 (ICOSLG, B7H2, B7RP1, ICOSL, KIAA0653)

Function

• ligand for the T-cell-specific cell surface receptor ICOS
• acts as a costimulatory signal for T-cell proliferation & cytokine secretion
• induces also B-cell proliferation & differentiation into plasma cells.
• may play role in mediating local tissue responses to inflammatory conditions, as well as in modulating the secondary immune response by co- stimulating memory T-cell function

Structure

• belongs to the immunoglobulin superfamily, BTN/MOG family
• contains 1 Ig-like C2-type domain
• contains 1 Ig-like V-type domain

Compartment

• membrane; single-pass type 1 membrane protein (putative)

Alternative splicing

• named isoforms=2
• additional isoforms seem to exist

Expression

• isoform 1 is widely expressed (brain, heart, kidney, liver, lung, pancreas, placenta, skeletal muscle, bone marrow, colon, ovary, prostate, testis, lymph nodes, leukocytes, spleen, thymus & tonsil)
• isoform 2 is detected only in lymph nodes, leukocytes & spleen
• expressed on activated monocytes & dendritic cells
• constitutive expression is further enhanced by TNF in peripheral blood B-cells & monocytes
• TNF decreases expression in dendritic cells

More general terms

• CD antigen
• immunoglobulin superfamily protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=23308
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:23308
• OMIM: https://mirror.omim.org/entry/605717
• UniProt: http://www.uniprot.org/uniprot/O75144.html