Messenger RNP

Messenger RNP (messenger ribonucleoprotein) is mRNA with bound proteins. mRNA does not exist 'naked' in vivo but is always bound by various proteins while being synthesized, spliced, exported, and translated in the cytoplasm. Messenger RNP (messenger ribonucleoprotein) is mRNA with bound proteins. mRNA does not exist 'naked' in vivo but is always bound by various proteins while being synthesized, spliced, exported, and translated in the cytoplasm. When mRNA is being synthesized by RNA polymerase, this nascent mRNA is already bound by RNA 5′ end 7-methyl-guanosine capping enzymes. Later, the pre-mRNA is bound by the spliceosome containing exon and intron definition complexes and proteins and RNA that catalyze the chemical reactions of splicing. Joan Steitz and Michael Lerner and collaborators showed that the small nuclear RNAs (snRNAs) are complexed into small nuclear Ribonuclear Proteins (snRNPs). Christine Guthrie and collaborators showed that specific snRNAs encoded by single copy genes in yeast base pair with the pre-mRNA and direct each step in splicing. The spliced mRNA is bound by another set of proteins which help in export from the nucleus to the cytoplasm. In vertebrates exon-exon junction are marked by exon junction complexes which in the cytosol can trigger nonsense mediated decay if the exon-exon junction is more than 50-55 nt downstream of the stop codon.