Purification and Properties of Ovalbumin Messenger RNA

Abstract

Ovalbumin messenger RNA was purified 67‐fold from hen oviduct polysomal RNA by sucrose gradient centrifugation and oligo(dT)‐cellulose hybridization. Ovalbumin messenger RNA activity was coincident with the main peak of absorbance after acrylamide gel electrophoresis of the purified RNA. Each purified messenger was translated over 20 times in a rabbit reticulocyte lysate, protein‐synthesizing system. An apparent molecular‐weight of approximately 875 000 was obtained by electrophoresis under both native and denaturing (formamide) conditions. In contrast, on sucrose gradients this messenger sedimented at approximately 15 S, corresponding to a molecular weight of about 550 000. Under certain conditions, ovalbumin messenger RNA activity was observed on both gels and gradients at a position approximately double these molecular weights. The larger messenger RNA species could be dissociated to the smaller one by either heating at 65 °C or formamide treatment, thus demonstrating messenger RNA aggregation. We conclude that ovalbumin messenger RNA contains between 1670 and 2640 nucleotides; a value significantly greater than the number (1161) that are translated into ovalbumin.