LOCALIZATION OF S1 AND ELONGATION FACTOR-1-ALPHA MESSENGER-RNA IN RAT-BRAIN AND LIVER BY NONRADIOACTIVE INSITU HYBRIDIZATION

Elongation factor-I alpha (EF-1alpha) is a ubiquitous, highly conserved protein that functions in peptide elongation during mRNA translation. We recently reported that, as do lower species, mammals also contain a second EF-1alpha-like gene (S1). Unlike EF-1alpha, which is present in all tissues, S1 mRNA is detected only in brain, heart, and muscle by Northern analysis and RNAse protection assays. In this report we present the identification of Sl and EF-1alpha. messages by non-radioactive in situ hybridization in brain and liver. We show that with this technique we can detect S1 mRNA only in certain cells in brain, mostly neurons; on the other hand, EF-1alpha is present in all cell types that we have studied so far. We demonstrate that although EF-1alpha mRNA can be detected in S1-negative cells it is also present in high abundance in SI-positive cells. The results presented here correlate with our previous finding that mammalian species contain a tissue-specific EF-1alpha-like gene, S1. The presence of a second EF-1alpha-like transcript within fully differentiated cells suggests a novel cell type-specific gene expression whose function may be related to the permanent growth-arrested state of cells in brain, heart, and muscle.