Alterations in the relative abundance of specific messenger ribonucleoproteins associated with compensatory renal hypertrophy.

A possible role of messenger RNA (mRNA)-associated proteins during compensatory renal hypertrophy in modulation of mRNA biogenesis has been examined in this investigation. Renal cytoplasmic free messenger ribonucleoprotein (CF mRNP) and polysomal mRNP (PA mRNP) have been isolated from kidney following 48 hours of compensatory renal hypertrophy, and the relative amounts of proteins associated with CF mRNP and PA mRNP in control and hypertrophying mouse kidney are compared. (CF mRNP refers to nonpolysomal messenger ribonucleoprotein found in the subribosomal region of sucrose gradients. PA mRNP or polysome-associated mRNP refers to mRNP released from polysomes.) CF mRNP has a buoyant density of 1.3 to 1.44 gm. per ml., contains RNA that sediments at 5 to 22 Svedberg units, and has a protein moiety comprising at least 15 polypeptides as revealed by sodium dodecyl sulfate polyacrylamide gels. PA mRNP contains three major polypeptides (molecular weights, 77,000, 52,000 and 17,000). Following 48 hours of compensatory renal hypertrophy, the relative amounts of proteins are changed: a 44,000- and 52,000- molecular weight polypeptide in CF mRNP is increased, a 52,000-molecular weight polypeptide in PA mRNP is reduced, and a 17,000-molecular weight polypeptide in PA mRNP is increased.