Characteristics of poly(A)-containing nuclear informosomes from wheat germ and the proteins contained in them

Purified preparations of poly(A)-containing nuclear informosomes from wheat germ and their poly(A)-protein fragments were isolated by chromatography on oligo (dT)-cellulose. Poly(A)-containing informosomes account for approximately 15% of the radioactivity of the rapidly labelled RNA of the nuclear extract; they have sedimentation coefficients from 10 to 80S and a buoyant density in a CsCl gradient of 1.40 g/cm3. Electrophoresis of the proteins of poly(A)-containing nuclear informosomes in polyacrylamide gel with SDS revealed two major polypeptides with M/sub r/ 34,000 and 52,000 and minor polypeptides with M/sub r/ 16,000, 23,000, 64,000 and 68,000. Nuclear informosomes contain protein-bound poly(A)-sequences (50-100 nucleotides long) resistant to pancreatic and Tl RNases. Poly(A)-protein fragments have a buoyant density in CsCl of 1.38 g/cm3, sedimentation coefficients of 4-12S in ribonucleoprotein form, and of 3-4S after deproteination. Poly(A)-protein complexes contain polypeptides with M/sub r/ 52,000, 64,000 and 68,000, the two with M/sub r/ 52,000 and 64,000 being most tightly bound to poly(A)