An alteration in the primary structure of a protein predicted on the basis of genetic recombination data.

MechanismS, Cold Spring Harbor Symposia on Quantitative Biology, vol. 26 (1961, in press). 7Yanofsky, C., D. R. Helinski, and B. Maling, in Cellular Regulatory Mechanisms, Cold Spring Harbor Symposia on Quantitative Biology, vol. 26 (1961, in press). 8 Henning, U., D. R. Helinski, F. C. Chao, and C. Yanofsky, J. Biol. Chem. (in press). Helinski, D. R., and C. Yanofsky, manuscript in preparation. Yanofsky, C., and I. P. Crawford, these PROCEEDINGS, 45, 1016 (1959). l' Maling, B. D., and C. Yanofsky, these PROCEEDINGS, 47, 551 (1961). 12 Allen, M., and C. Yanofsky, unpublished experiments. 13 Initial studies involving the A-il protein were performed on the protein isolated from the mutant A-li; however, since the A protein of the double mutant A-11-46 is more stable than the A-li protein, the double mutant protein was used in later studies on the A-li amino acid change. Similarly, in studies on the A-23 protein, the initial studies were performed with the protein from the mutant A-23. Later studies were carried out on the more stable A protein obtained from the double mutant A-3-23. In each case, the peptide pattern difference characteristic of the mutant in question was found to be present in the corresponding double mutant peptide pattern.7 14 Helinski, D. R., and C. Yanofsky, unpublished experiments. 15 Hirs, C. H. W., S. Moore, and W. H. Stein, J. Biol. Chem., 235, 633 (1960). 16 Carlton, B. C., and C. Yanofsky, unpublished experiments. 17 Acher, R., and C. Crocker, Biochim. et Biophys. Acta, 9, 704 (1952). 18 Henning, U., and C. Yanofsky, these PROCEEDINGS, 48, 183 (1962). 19 Neurath, H., and G. W. Schwert, Chem. Revs., 46, 69 (1950). 10 Yanofsky, C., and E. S. Lennox, Virology, 8, 425 (1959).