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. When expressed in rat HTC4 hepatoma cells, is capable of mediating S1P-induced cell proliferation and suppression of apoptosis. Expressed in all tissues, but most abundantly in heart, placenta, kidney, and liver. Belongs to the G-protein coupled receptor 1 family.