What is the Difference Between Polysome Profiling and Ribosome Profiling

The key difference between polysome profiling and ribosome profiling is that polysome profiling analyzes ribosome behavior using both ribosome and mRNA (polysome) during translation, while ribosome profiling analyzes ribosome behavior only using the mRNA sequence during translation.

Translation is the second phase of protein synthesis that converts the information in the mRNA to an amino acid sequence. Translatomics is a study of ORFs (open reading frames) that are actively translated in a cell of an organism. Polysome and ribosome profiling techniques are two types of techniques in the field of molecular biology to assess and infer different parameters in the context of analyzing the translatome.

CONTENTS

1. Overview and Key Difference
2. What is Polysome Profiling
3. What is Ribosome Profiling
4. Similarities – Polysome Profiling and Ribosome Profiling
5. Polysome Profiling vs Ribosome Profiling in Tabular Form
6. Summary – Polysome Profiling vs Ribosome Profiling

What is Polysome Profiling?

Polysome profiling is a technique that infers the status of translation of a specific mRNA by analyzing the behaviour of both ribosome and mRNA (polysome). In other words, this technique provides data and conclusions on the association of mRNAs with ribosomes. The polysome refers to the group of ribosomes bound to an mRNA that is present during the elongation phase of translation.

Polysome profiling requires the cell lysate, which is then centrifuged. The centrifuged sample is then separated based on their densities to characterize the small and large subunits of the ribosomes and the corresponding mRNA involved in the formation of the polysome. Furthermore, the process also involves measuring optical density. Experts are required to perform polysome profiling.

Polysome profiling technique is an important tool for many applications. Scientists use this technique to study the degree of translation in cells. More specifically, it is a tool to provide accurate information on the study of individual proteins and their specific mRNAs. In the context of studying the degree of translation of a particular mRNA, the polysome profiling technique is vital. Here, the 3’ and 5’ sequences of an mRNA can be investigated with reference to their effects on the amount of mRNA produced and the level of translation.

What is Ribosome Profiling?

Ribosome profiling is a technique that analyzes the behaviour of the ribosome with respect to its mRNA during translation. This technique was found and developed by Joan Steitz and Marilyn Kozak. Later this technology was further developed by two scientists, Nicholas and Jonathan, in combination with next-generation sequencing, which led to the development of different related techniques such as Translating Ribosome Affinity Purification (TRAP) methodology.

The procedure of ribosome profiling involves isolating the mRNA, removing the RNA that’s not bound to ribosomes, and separating the mRNA bound to ribosomes. Following this procedure, the mRNA isolate is reverse transcribed, and cDNA synthesis takes place. Finally, sequence data can be aligned with the translational profile to deduce the characteristics of the ribosome behaviour with respect to the mRNA.

Ribosome profiling helps many researchers to identify and infer the location of start sites of translation, the complement of translated open reading frames (ORFs) in a cell or a tissue, the distribution of ribosomes on mRNA, and the rate of translating ribosomes. Ribosome profiling is also known as ribosome footprinting or Ribo Seq.

What are the Similarities Between Polysome Profiling and Ribosome Profiling?

• Polysome and ribosome profiling are molecular biological techniques important in research.
• They provide information on the translation process.
• Both profiling processes provide data through analysis of the translatome.
• Professional experts are needed to perform both techniques for accurate results.
• Bioinformatics tools play an important role in both techniques.

What is the Difference Between Polysome Profiling and Ribosome Profiling?

Polysome profiling analyzes the ribosome behaviour using both ribosome and mRNA (polysome) during translation, while ribosome profiling analyzes the ribosome behaviour only using the mRNA sequence during translation. Thus, this is the key difference between polysome profiling and ribosome profiling. Moreover, polysome profiling involves techniques like density gradient centrifugation and optical density measurements, while ribosome profiling involves mRNA extraction and sequencing techniques. Also, ribosome profiling is more accurate than polysome profiling.

The below infographic presents the differences between polysome and ribosome profiling in tabular form for side by side comparison.

Summary – Polysome Profiling vs Ribosome Profiling

Translation is the second phase of protein synthesis that involves converting the information on the mRNA sequence to an amino acid sequence. This process requires an mRNA template, ribosomes, amino acids, tRNA, and other factors. Polysome and ribosome profiling are two molecular techniques. Polysome profiling analyzes the ribosome behaviour using both ribosome and mRNA (polysome) during translation, while ribosome profiling analyzes the ribosome behaviour only using the mRNA sequence during translation. Polysome profiling involves techniques like density gradient centrifugation and optical density measurements. Ribosome profiling involves techniques like mRNA extraction, cDNA synthesis, and sequencing. So, this summarizes the difference between polysome profiling and ribosome profiling.

Reference:

1. Chassé, Héloïse, et al. “Analysis of Translation Using Polysome Profiling.” Nucleic Acids Research, 2016.
2. Jin, Hyun Yong, and Changchun Xiao. “An Integrated Polysome Profiling and Ribosome Profiling Method to Investigate in Vivo Translatome.” Methods in Molecular Biology, 2017, pp. 1–18., https://doi.org/10.1007/978-1-4939-7514-3_1.

Image Courtesy:

1. “Important translatomics techniques” By Polyribosome – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “RibosomeProfilejpg” By DennisPietras – Own work (CC BY-SA 4.0) via Commons Wikimedia