Fig. 5.

RASA3 is lost during reticulocyte maturation through the exosomal pathway. (A) In WT red cells, RASA3 is found in very few cells that are also positive for the TfR by immunofluorescence. (B) After erythropoietic stress by phlebotomy and isolation of reticulocytes on a Percoll gradient, a strong staining for RASA3 is observed on the plasma membrane and in some internal compartments where it colocalizes with the TfR (white arrows). Mature red cells, assessed by negative staining of the TfR (red arrow) are also negative for RASA3. (C) Western blot analyses of reticulocytes and mature erythrocytes (RBC) show that RASA3 is lost during reticulocyte maturation, and (D) is associated with exosomes secreted during maturation.