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RNA Splicing

RNA Splicing

Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...

RNA Splicing

RNA Splicing

Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...

Pre-mRNA Processing: RNA Splicing

Pre-mRNA Processing: RNA Splicing

Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...

Alternative RNA Splicing

Alternative RNA Splicing

Alternative RNA splicing is the regulated splicing of exons and introns to produce different mature mRNAs from a single pre-mRNA. Unlike in constitutive splicing where a single gene produces a single type of mRNA, alternative splicing allows an organism to produce multiple proteins from a single gene and plays an important role in protein diversity.
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...

Alternative RNA Splicing

Alternative RNA Splicing

Alternative RNA splicing is the regulated splicing of exons and introns to produce different mature mRNAs from a single pre-mRNA. Unlike in constitutive splicing where a single gene produces a single type of mRNA, alternative splicing allows an organism to produce multiple proteins from a single gene and plays an important role in protein diversity.
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...

Exon Recombination

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...

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Related Experiment Video

Updated: Jun 30, 2026

ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast

ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast

Published on: June 30, 2022

Primordial spliceosomal introns were probably U2-type.

Malay Kumar Basu¹, Igor B Rogozin, Eugene V Koonin

¹National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA.

Trends in Genetics : TIG

|October 1, 2008

Summary

Primordial spliceosomal introns were likely U2-type, not U12-type. Analysis of conserved intron positions and amino acid distributions supports this evolutionary conclusion for eukaryotic gene structure.

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A Reporter Based Cellular Assay for Monitoring Splicing Efficiency

A Reporter Based Cellular Assay for Monitoring Splicing Efficiency

Published on: September 15, 2021

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Last Updated: Jun 30, 2026

ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast

ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast

Published on: June 30, 2022

A Reporter Based Cellular Assay for Monitoring Splicing Efficiency

A Reporter Based Cellular Assay for Monitoring Splicing Efficiency

Published on: September 15, 2021

Area of Science:

Molecular Biology
Evolutionary Biology
Genetics

Background:

Eukaryotic genomes contain two main types of spliceosomal introns: U2 and U12.
These intron types differ in their splice signals and are processed by distinct spliceosomes.
The evolutionary origin of these intron types is not fully understood.

Purpose of the Study:

To investigate the nature of primordial spliceosomal introns.
To determine whether primordial introns were U2-type or U12-type.

Main Methods:

Comparative analysis of amino acid distributions at intron insertion sites.
Examination of intron positions conserved throughout eukaryotic evolution.
Comparison with human and Arabidopsis thaliana U2 and U12 intron distributions.

Main Results:

Amino acid distributions at conserved intron insertion sites showed high similarity to U2-type introns.
No significant similarity was found with U12-type introns.
Intron positions retained across eukaryotic evolution provided key evolutionary markers.

Conclusions:

The findings strongly suggest that primordial spliceosomal introns were predominantly U2-type.
This indicates a specific evolutionary trajectory for intron types in eukaryotes.
The study provides insights into the early evolution of eukaryotic gene splicing mechanisms.