Patterns of expression of erythroblast non-globin mRNAs.

Three classes of erythroblast non-globin mRNAs have been identified using cDNA recombinants isolated from a mouse foetal liver cDNA library. One erythroid cell-specific 12S mRNA coding for a 16-19,000 dalton protein has been identified using two independent cDNA recombinants (pFC5 and pFA6). The gene encoding this mRNA is unique in the genome and its organisation seems to be the same in both erythroid and non erythroid cell genomic DNA as judged by digestion with restriction enzymes and Southern blotting. Another erythroblast mRNA of size 16S represented by recombinant pFD12 is expressed in brain cells as well as a variety of haemopoietic cell types, but not in adult liver or fibroblasts. Two other erythroblast mRNAs of size 8S and 12S represented by recombinants pD6 and pA4 are expressed in many differentiated cell types with the exception of non-dividing cells such as reticulocytes, peripheral white blood cells, adult liver and brain cells. These mRNAs are, therefore, presumed to be involved ubiquitously in cell proliferation or general cell metabolism.