Basic Protein Synthesis Research Articles

Cytoplasmic and nuclear basic protein synthesis during early sea urchin development

Nuclear and cytoplasmic basic proteins were isolated from three early developmental stages of Strongylocentrotus purpuratus following a 1-h incubation in 14C-amino acids. The absorbance profiles of electrophoretically separated basic nuclear proteins from zygote and 32–64-cell stages are very similar. Both stages have three peaks of 14C-incorporation. One peak coincides with the F3 bands of carrier blastula histone and the other two peaks directly precede it. Very little absorbancy or radioactivity are associated with the other fractions of carrier histone. Blastulae raised in the continuous presence of actinomycin D contain nearly the same histone pattern as controls raised without the drug. This demonstrates that histones are translated during early development using stored maternal messages. Acid extracts of the crude microsomal fraction from 32–64-cell and blastula stages contain several very radioactive basic protein bands. These active proteins are extracted with the non-labeled ribosomal basic proteins and have the same electrophoretic mobilities as histones. Since similar migrating fractions are found in nuclei of blastulae but not the 32–64-cell stage, it is suggested that histones are made during early cleavage, but only a small portion immediately become an integral part of chromatin. The remaining fractions may be held in the cytoplasm for several cell divisions before becoming incorporated into chromatin at the onset of blastulation.

Deoxycytidine-stimulated basic protein synthesis in amphibian oocytes

Deoxycytidine stimulated the incorporation of 3H-lysine in nucleoprotein extracted by 2 M NaCl. Further characterisation steps showed that an important part of the radioactivity was confined to an acid-extractable or trypsin-released acid-soluble fraction, indicating a dibasic amino acid rich protein. Increase of 3H-lysine incorporation into this fraction was stimulated by CdR at 0.5 mM while increase in specific radioactivity of total nucleoprotein extended up to 1.5 mM. While incomplete separation of follicle cells and oocyte content is always the limitation inherent in oogenesis study, results from sucrose gradient centrifugation indicated that at least part of the radioactivity was found in particles other than follicle cell and ovarian tissue nuclei. CdR may help to build up an increased deoxyriboside triphosphate pool through the enzymatic reduction of riboside diphosphates [16]; thus promoting cDNA neosynthesis, which in turn stimulates an increase in basic protein synthesis. A direct relationship between the synthesis of cDNA and cytoplasmic basic protein is under investigation.

Changes in protein spectra of bean seed during germination

Globulins, albumins, and basic proteins were extracted from seeds of red kidney bean (Phaseolus vulgaris), and their distribution was in a ratio of about 3:2:1, respectively. The globulin fraction constituted a major portion of the reserve proteins and was hydrolyzed rapidly during germination. More than 90% of the basic proteins, extractable with 0.05 N acetic acid, disappeared 12 days after germination. Although the decrease in total albumin was not as marked as with the other two fractions, a number of components of this fraction disappeared during the early stages of germination, but several new components were detected about 8 days after germination. The apparent synthesis of new globulin components during germination was also observed, but no synthesis of basic protein could be detected.

Glial cells and the central myelin sheath.

Glial cells and the central myelin sheath.