Background of the antigen
CYTIP is a cytoplasmic protein that is involved in lymphocytic cell adhesion. Expressed primarily in hematopoetic cells, CYTIP regulates the activity of cytohesin-1 (an integrin-activating protein involved in cell adhesion) by mediating its recruitment to the leukocyte membrane. Through its ability to bind cytohesin-1, CYTIP is able to sequester it to the cytoplasm, thereby preventing cytohesin-1 translocation to lymphocytes and interrupting the flow of information in the cell adhesion pathway. CYTIP can be recruited from the cytoplasm to the membrane by leukocyte integrins which interact with CYTIP through its PDZ domain. After membrane translocation, CYTIP can be re-located to the cytoplasm via exposure to a phorbol ester. Additionally, CYTIP associates with SNX27 (sorting nexin 27) and helps to coordinate trafficking and signaling complexes. Up-regulation of CYTIP is observed in maturing dendritic cells, suggesting a possible role in developmentally-controlled cell adhesion.
