Isolation of messenger RNA coding for the "fast" protein of embryonic chick feathers

The messenger RNA coding for the "Fast" protein of embryonic chick feathers has been purified from the overwhelming relative amounts of keratin mRNA which are present in the developing feathers. The "Fast" protein mRNA represents about 4-8% of the total mRNA population of the feather. Despite differences between the size of the "Fast" proteins and the keratins the two mRNA species are very similar in molecular weight as judged by electrophoresis under denaturing conditions. However, by electrophoresis in 8 M urea gels at 55 degrees C, the "Fast" protein mRNA could be separated from keratin mRNA, presumably reflecting differences in messenger RNA secondary structure.