DNA-binding proteins of Xenopus laevis: synthesis during oogenesis-ovulation and early embryogenesis

DNA-binding proteins of Xenopus laevis synthesized during two periods of early development (oogenesis-ovulation and early embryogenesis) were co-chromatographed on DNA-cellulose. Proteins with an affinity for DNA were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Most of the proteins eluted from DNA-cellulose with 0.6 M NaCl had mol. wts less than 40 000; some of these proteins were synthesized to a greater extent by developing embryos than by oocytes. A DNA-binding protein or group of proteins with a mol. wt of approx. 70 000 was synthesized during oogenesis-ovulation but not during embryogenesis. Differential labeling of developing embryos with ${}^3\text{H}\text{]}\text{tryptophan}$ and ${}^{14}\text{C}\text{]}\text{lysine}$ indicated that some of the low mol. wt DNA-binding proteins are histones. Some of these proteins also incorporated monosodium ${}^{32}\text{P}\text{]}\text{phosphate}$. A greater fraction of the proteins synthesized by oocytes and developing embryos were bound to DNA-histone-cellulose than to DNA-cellulose. A group of low mol. wt proteins made during oogenesis-ovulation were bound more to DNA-histone-cellulose than were proteins with similar mol. wts made by developing embryos.