RNA SPLICING AND PROCESSING

The physical form of hnRNA is hnRNP.hnRNP= Core proteins plus others = ~20 proteinsTypically proteins are present at ~10 8 copies per nucleus, compared with~10 6 molecules of hnRNA.The most abundant proteins in the particleare the core proteins, but other proteinsare present at lower stoichiometry, makinga total of ~20 proteins. The proteinstypically are present at ~108 copies pernucleus, compared with ~106 molecules ofhnRNA. Some of the proteins may have astructural role in packaging the hnRNA;several are known to shuttle between thenucleus and cytoplasm, and play roles inexporting the RNA or otherwise controllingits activityFigure 24.1 hnRNA exists as a ribo-nucleoprotein particle organized asa series of beads.B-3