CD155

CD155 (cluster of differentiation 155) also known as the poliovirus receptor is a is_associated_with::protein that in humans is encoded by the PVR is_associated_with::gene.

Function
CD155 is a Type I is_associated_with::transmembrane is_associated_with::glycoprotein in the is_associated_with::immunoglobulin superfamily. Commonly known as Poliovirus Receptor (PVR) due to its involvement in the cellular is_associated_with::poliovirus infection in primates, CD155's normal cellular function is in the establishment of intercellular is_associated_with::adherens junctions between is_associated_with::epithelial cells. The role of CD155 in the is_associated_with::immune system is unclear, though it may be involved in intestinal humoral immune responses. Subsequent data has also suggested that CD155 may also be used to positively select MHC-independent T cells in the thymus.

The external domain mediates cell attachment to the is_associated_with::extracellular matrix molecule is_associated_with::vitronectin, while its intracellular domain interacts with the is_associated_with::dynein light chain Tctex-1/is_associated_with::DYNLT1. The gene is specific to the primate lineage, and serves as a cellular receptor for poliovirus in the first step of poliovirus replication.

Structure
CD155 is a transmembrane protein with 3 extracellular immunoglobulin-like domains, D1-D3, where D1 is recognized by the virus.

Low resolution structures of CD155 complexed with poliovirus have been obtained using electron microscopy while a high resolution structures of the is_associated_with::ectodomain D1 and D2 of CD155 were solved by x-ray crystallography.