Identification of spectrin and protein 4.1-like proteins in mammalian lens

Human, bovine, canine, and rabbit lenses were found to contain proteins which cross-react with anti-4.1 serum and which have molecular weights similar to erythrocyte proteins 4.1a and 4.1b (approximately 80 kd). Additionally, bovine, canine, and rabbit lenses contain a 4.1-like protein of approximately 125 kd which is absent from human lens. Proteins which cross-react with antibody to human erythrocyte spectrin were also detected. The human lens showed weak cross-reaction of bands of 240 kd and 225 kd, and a more intense cross-reaction of a band of 235 kd. Canine and bovine lenses showed weak cross-reaction with only the bands at 240 kd and 235 kd. The lens 240 kd band of all species also demonstrated calcium-dependent binding of calmodulin. Our results indicate that proteins related to, but distinct from, erythrocyte protein 4.1 and spectrin are found in mammalian lens.