SEVERAL WEAK SIGNALS IN THE CYTOSOLIC AND TRANSMEMBRANE DOMAINS OF THE INTERLEUKIN-2-RECEPTOR BETA-CHAIN ALLOW FOR ITS EFFICIENT ENDOCYTOSIS

Plasma membrane receptors are retrieved continually from the cell surf ace by endocytosis and transported to intracellular organelles. They a re internalized at various rates depending on their ability to interac t with endocytic structures of the plasma membrane. The interleukin-2- receptor beta chain is endocytosed constitutively and efficiently. Her e we show that different motifs in its cytosolic tail promote entry in an additive way, each of them acting as a weak internalization signal . The transmembrane domain of beta also participates in endocytosis. I n conclusion, several weak endocytic determinants can be responsible f or the rapid internalization of a membrane protein.