The capacity of basic peptides to trigger exocytosis from mast cells correlates with their capacity to immobilize band 3 proteins in erythrocyte membranes.

The effect of mast-cell-triggering peptides on the rotational properties of band 3, a protein component of the human erythrocyte membrane, was measured by observing flash-induced transient dichroism of the triplet probe eosin maleimide. In the presence of melittin, polylysine and five synthetic peptides, varying degrees of retardation in the rotational motion of band 3 were produced. When placed in order of band 3 immobilizing activity, the peptides formed a series identical with their order of efficacy in releasing 5-hydroxytryptamine from rat peritoneal mast cells. The correspondence in the abilities to immobilize band 3 in the erythrocyte and trigger mast cells is significant because structure-activity analyses of the peptides show both processes to have the same cationic, hydrophobic and stereochemical requirements. Probably, the immobilization of band 3 proteins reflects an ability of the basic peptides to aggregate anionic surface moieties, and therefore a similar mechanism is implied in mast-cell triggering.