Receptor for the lysosphingolipid sphingosine 1-phosphate (S1P). S1P is a bioactive lysophospholipid that elicits diverse physiological effect on most types of cells and tissues. May be involved in cell migration processes that are specific for lymphocytes. Specifically expressed in fetal and adult lymphoid and hematopoietic tissue as well as in lung. Considerable level of expression in adult and fetal spleen as well as adult peripheral leukocytes and lung. Lower expression in adult thymus, lymph node, bone marrow, and appendix as well as in fetal liver, thymus, and lung. Belongs to the G-protein coupled receptor 1 family.