Heterogeneity in the β-subunit of translational initiation factor eIF-2 during brain development

摘要

We have detected by immunoblotting analysis of crude fractions from suckling and adult rat brain, resolved by two-dimensional isoelectric focusing-dodecyl sulfate polyacrylamide gel electrophoresis, the presence of two different forms of the β subunit of polypeptide initiation factor 2 (eIF-2). These two forms differ in their apparent molecular weights and also in their isoelectric point values. Quantitation of both forms in the crude fractions shows that, the most basic form β1(pI: 6.1, 52 kDa), is present in higher levels of the salt wash ribosomal fractions obtained from both, suckling and adult animals, than in the postmicrosomal fraction corresponding to the same animals. The most acidic form, β2(pI: 5.9, 50 kDa), is present in the highest level in the postmicrosomal supernatant from adult animals. A close parallelism is found between β1levels and eIF-2 activ