Thomas Cech, in 2009, proposed the existence of the RNP world after his observation of apparent differences in the composition of
catalysts in the two most fundamental processes that maintain and express genetic systems. For DNA, the maintenance, replication, and transcription processes are accomplished purely by protein
polymerases, not by self-catalysis. However, the
mRNA processes of gene expression via splicing and protein synthesis are catalyzed by RNP complexes (the
spliceosome and
ribosome). This difference between protein and ribonucleoprotein catalysts can be explained by extending the
RNA world theory. The older RNA molecules were originally self-catalyzed through
ribozymes, with a single type of molecule serving both as information templates and metabolic catalysts. RNA then evolved the assistance of proteins to form RNP. Thereafter, the newer DNA molecule used only the more efficient protein processes from the start. Thus, our current DNA world could have resulted from the gradual replacement of RNA catalysis machines with proteins. In this view,
ribonucleoproteins and nucleotide-based cofactors are remnants of an intermediary era, the RNP world. == See also ==