RGS18: Proteins and Enzymes

Regulators of G-protein signaling (RGSs) are a protein family that can act as GTPase-activating proteins for G(alphai)- and G(alphaq)-class proteins. They accelerate transit through the cycle of GTP binding and hydrolysis and thereby accelerate signaling kinetics and termination. One of these proteins, RGS18, is a 235 amino acid protein that is closely related to RGS5 (46% identity) and approximately 30-40% identity to other RGS proteins. This protein is expressed in platelet, leukocyte, and megakaryocyte cell lines. Engagement of TLR3 or TLR4 on monocyte-derived DCs potently down-regulates RGS18 and RGS14 without modifying other RGS proteins. A similar pattern of RGS protein expression occurs in immature bone marrow-derived mouse DCs stimulated to mature via TLR4 signaling. The changes in RGS18 and RGS1 expression are likely important for DC function.