The ribonucleoprotein structures along the pathway of mRNA formation.

Heterogeneous nuclear RNAs (hnRNAs), some of which are mRNA precursors, and the mature mRNAs are associated in eukaryotic cells with specific proteins to form ribonucleoprotein complexes (RNP). The RNP proteins are likely to play a major role in the formation, packaging, processing, and function of mRNA. The major proteins that interact with hnRNA and with mRNA were identified by photochemical RNA-protein cross-linking in intact cells and monoclonal antibodies to several of these proteins were produced. Using these antibodies the hnRNP proteins were characterized and the hnRNP complex was isolated from vertebrate cell nuclei. The hnRNP complex is a unitary structure of consistent, defined and conserved components. The proteins of the hnRNP complex were identified and the general organization of hnRNA and proteins in the hRNP complex were studied.