sphingosine-1-phosphate receptors are a group of proteins found on the surface of cells that play a crucial role in various biological processes. They are activated by a lipid molecule called sphingosine-1-phosphate, which is involved in regulating cell growth, survival, and movement. These receptors are important for maintaining the immune system and are also implicated in various diseases. There are five known types of sphingosine-1-phosphate receptors, labeled S1P1 to S1P5. Each type has distinct functions and is distributed differently throughout the body. For example, S1P1 is primarily involved in lymphocyte trafficking, while S1P3 is associated with cardiovascular functions. Understanding these receptors can help in developing targeted therapies for conditions like autoimmune diseases and cancer.