Membrane proteins of the erythrocytes of bullfrog, Rana catesbeiana, and its tadpole

Abstract 1. 1. The plasma membranes of the nucleated erythrocytes from adult frog and tadpole of Rana catesbeiana were isolated to be substantially free from the nuclear and mitochondrial membranes by means of sucrose density gradient centrifugation. 2. 2. SDS-polyacrylamide gel electrophoresis revealed that the erythrocyte membrane of frog was distinct from that of tadpole in its protein composition in band 4.5 region on the electrophoretic profile; the former showed three bands, named 4.5 a, b and c, while the latter showed a large amount of the band 4.5 b alone. 3. 3. Two different erythrocytes, tadpole and frog type, coexist in the circulation of tadpoles undergoing metamorphosis.