Cell-free hemoglobin-synthesizing systems from erythrocytes of 4- and 17-day chick embryos have been developed. These systems have been used to investigate possible structural and functional differences in factors involved in protein synthesis obtained from these different developmental stages. Each cell-free system consists of three major cellular fractions i.e., the S-100 supernatant, the salt-washed ribosomes, and the 0.5 m KCl ribosomal wash. When the ribosomal wash fraction from one developmental stage is included in a cell-free system containing ribosomes and S-100 supernatant from the other developmental stage, a drastic reduction in the kinetics of [3H]leucine incorporation into globin products is observed, when compared to the homologous control cell-free systems. A similar depression of the kinetics of incorporation is observed when the mixed component is either the S-100 supernatant or the ribosomes. Control rates of incorporation can be reestablished when the corresponding homologous component is added back to the incubation mixture. The predominant types of hemoglobins produced in the salt-wash heterologous systems are those hemoglobins characteristic of the developmental stage of the salt wash. This seems to imply that the ribosomal salt-wash fraction may possess developmental stage specificity for the globins.
ASJC Scopus subject areas
- Molecular Biology