RNA splicing is a post transcriptional modification through which a precursor messenger RNA (pre-mRNA) turns into a mature functional RNA. Here we are going to discuss all the RNA splicing functions in a cell.
RNA splicing is one of the most significant events after the transcription process, it enhances the productivity of RNA molecules. Among several RNA splicing functions, some key functions are mentioned below.
Converting pre-mRNA or hnRNA to mature RNA
The RNA splicing mechanism cuts out the non coding sequences or introns from between the coding sequences or exons in the precursor messenger RNA or pre mRNA. This removal enhances the efficiency and productivity of that molecule when translated. This way the RNA splicing functions and converts pre mRNA or hn RNA into a mature RNA.
Forming different exon combinations
In alternative splicing mechanism first the non coding sequences or introns are removed from between the exons. After that the splicing mechanism combines different exon units with each other, creating different combinations of them.
Synthesizing multiple mRNA from single transcript
One of the crucial RNA splicing functions is to create multiple mRNA from a single transcript. Specifically in alternative splicing mechanism the introns are removed between the exons and the exons bind with each other in different combinations (isoforms). Which generates different functional proteins. That’s how a single transcript can generate multiple mRNA isoforms.
Inserting new exons into introns
During the RNA splicing process new exons can also be inserted into the previous introns to make the gene sequence more modular. It increases protein diversity by creating new gene sequence combinations.
Increasing protein diversity
Through a splicing mechanism a single transcript is able to code for multiple functional proteins, without disrupting the original transcript structure. The more splicing occurs, the more proteins can be translated from a single precursor mRNA. Diversity in gene sequences or diversity in functional proteins ultimately leads the pathway to evolulation.
Assisting evolution process
The RNA splicing function also possesses some evolutionary significance in it. As we know prokaryotic cells splicing is very rare and in eukaryotic cells we can see the RNA splicing which increases protein diversity of a cell. Thus the splicing process helps a cell or organism to evolve according to the circumstances, by forming different functional proteins.
Regulating gene expressions and cellular Protein elements
Splicing can also regulate gene expression of cells. In alternative splicing, the mechanism determines isoforms of gene sequence by creating exon combinations from one transcript. This way it controls all the mRNA sequences which are to be translated into proteins. Thus, splicing controls and regulates all the protein substances of the cell.
Involves in protein binding
Alternative splicing also influences Protein binding mechanisms. After translation it is involved in protein-protein binding process, nucleic acid and protein binding process, Protein and membrane binding process as well.
Regulating protein elements
RNA splicing or we can say alternative splicing regulates several actions of proteins after translation. It determines the localisation of protein elements and also the properties of Proteins. Alternative splicing influences protein interactions with their ligands.
RNA splicing also impacts cellular activities and properties such as cell proliferation and cell survival.
RNA splicing mostly occurs in eukaryotic cells. In prokaryotes it is very rare. After the transcription process precursor mRNA or pre-mRNA undergoes post transcriptional modification. After completing the splicing mechanism the mature mRNA travels into the cytoplasm.
RNA splicing function from Wikimedia Commons
To know more read on RNA Splicing Steps: Detailed Analysis And Facts
microRNA splicing function
microRNAs or miRNAs are small (length about 22 nucleotides) single stranded RNA molecules which do not code for any Protein molecules. It plays a significant role in the splicing and gene expression process.
microRNA or miRNA regulates transcription and activates translation in presence of some special circumstances. It controls gene expressions as well. It controls deadenylation and methylation processes also.
The miRNAs transcribed from DNA sequence. It Undergoes splicing mechanism and turns into mature miRNA. It makes base pairs with mRNA sequences for functioning.
miRNA function from Wikimedia Commons
snRNPs function in rna splicing
SnRNPs stands for small nuclear ribonucleoproteins, spliceosomes.
The main function of snRNPs in RNA splicing is the removal of introns between the exons. Along with other spliceosomal units, snRNPs follow a two step transesterification process. At first step the 3′-hydroxyl of an adenosine attacks 5′ splice site and at second step 3′-hydroxyl of the producing 5′ exon attacks 3′ splice site, causing removal of an intron from between the exons. This way snRNP functions and produces a mature RNA from the precursor one.
How does RNA splicing work?
The RNA splicing works by following some specific steps, let’s have a closer look at them.
- The RNA splicing mostly regulates by a protein complex called spliceosome. In the case of the self splicing mechanism ribozymes regulate the splicing process.
- At First the spliceosome binds with the precursor RNA in the splice sites and performs its two step transesterification process.
- In this process the 2′-hydroxyl of an adenosine causes a nucleophilic attack in the 5′ splice site, creating a loop.
- In the second step the 3′-hydroxyl of the producing 5′ exon attacks 3′ splice sites and causes the removal of the intron.
- After that the exon segments attached with each other forming the mature RNA.
Most of the splicing mechanisms follow more or less these steps during splicing. In case of alternative splicing the mechanism is more complex than others. It creates different combinations or isoforms from a single transcript by removing introns, inserting exons and many more. In self splicing the introns are capable of mediating their excision and subsequent ligation.
RNA splicing function via spliceosome from Wikimedia Commons
As a whole we can say that RNA splicing is a very significant post transcriptional modification. Here we discuss some most common RNA splicing functions. We also mention how the RNA splicing functions regarding every step of it. Hope this article about RNA splicing function will be helpful to you.
To know more about RNA see our article on Is RNA Antiparallel: What, Why, Detailed Facts