The role of spectrin in erythrocyte ghost endocytosis.

Endocytosis in white ghosts prepared from human erythrocytes was induced by three methods: incubation with Mg-ATP, incubation with 0.1 mM EDTA, and digestion with 20 nanograms (ng.) per ml. of trypsin. In each case the endocytic vacuoles that were produced when separated and analyzed on SDS-polyacrylamide gel electrophoresis were found to be depleted of spectrin. This observation suggested that a requirement for endocytosis is the establishment of spectrin-free domains in the membrane. This hypothesis was tested by pre-incubating ghosts with anti-spectrin antibodies. Pre-incubation with anti-spectrin antibody blocked white ghost endocytosis produced either by Mg-ATP, EDTA, or trypsin. Therefore, it is proposed that spectrin has a key role in the endocytosis process.