Molecular weights, poly(A)--content, and partial separation of chick globin mRNAs

Area of Science:

• Molecular Biology
• Biochemistry

Background:

• Chick reticulocyte 9S RNA contains globin messenger RNA (mRNA).
• Understanding mRNA structure-function relationships is crucial for gene expression studies.

Purpose of the Study:

• To investigate the molecular basis for the separation of chick reticulocyte 9S RNA into distinct fractions.
• To correlate these fractions with their translational activity and poly(A) tail characteristics.

Main Methods:

• Electrophoresis of poly(A)-containing 9S RNA on formamide-polyacrylamide gels.
• In vitro translation using a wheat germ cell-free system.
• Hybridization with labeled poly(U) to determine poly(A) lengths.

Main Results:

• 9S RNA separated into three fractions with molecular weights around 211,000 daltons.
• Lower molecular weight fractions showed higher alpha-chain synthesis (up to 95%) and lower beta-chain synthesis.
• Higher molecular weight fractions showed decreased alpha-chain synthesis (60%) and increased beta-chain synthesis.
• Average poly(A) tail length decreased from 83 nucleotides (fraction I) to 36 nucleotides (fraction III).

Conclusions:

• Fractionation is influenced by variations in the non-poly(A) regions of alpha and beta-globin mRNAs.
• Differences in poly(A) tail lengths also contribute to the observed fractionation.
• These findings elucidate the heterogeneity within avian 9S globin mRNA populations.