A comparison of the proteins found in developing wild type larvae and developing lethal mutant larvae of Drosophila melanogaster.

Extracts of late larval lethal mutants were compared with extracts of wild type larvae of the same developmental age on double diffusion plates using 16 different antisera. Nearly all of the mutant extracts showed relative antigen concentration differences compared with the wild type and four of the mutants lacked a protein at death found in the wild type of the same developmental age. In each case it was a different protein. The results are discussed by considering the different ways in which mutations can lead to the loss of a protein in developing systems.