Abstract

A ribonuclease activity that has characteristics expected for an enzyme that catalyzes the regulated destabilization of serum protein-coding mRNAs following estrogen administration was previously identified on Xenopus liver polysomes. This enzyme activity is estrogen inducible and selectively degrades mRNAs (e.g., albumin, γ-fibrinogen) that are unstable following estrogen administration to male frogs. This paper reports on the relationship between this enzyme activity and the association of 40S and 60S ribosomal subunits. Ribonuclease activity (as defined by the generation of a specific cleavage fragment from albumin RNA) is found in polysome fractions that contain the majority of the liver mRNA. This activity sediments on sucrose gradients with the large polysome complexes observed in liver of vitellogenic animals. EDTA treatment generates 40S and 60S ribosome subunits and a significant amount of 80S ribosome monomers. Under these conditions, polysomal ribonuclease activity is found both free in solution and with the 80S material. Puromycin treatment generates predominantly 40S and 60S ribosomal subunits. Polysomal ribonuclease activity is found only in solution following puromycin treatment. These data indicate that the Xenopus liver polysomal nuclease requires the association of both ribosomal subunits for complex formation with polysomes. The polysomal nuclease behaves as a basic protein on Mono Q chromatography, with the fractionated material retaining the same differential activity toward albumin versus ferritin mRNA.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.