What is the alternative splice mechanism

Alternative splicing

Synonym: alternative splicing

1 definition

The alternative splicing is a special process in the context of transcription in the protein synthesis of eukaryotes. Viruses that attack eukaryotes also use this mechanism. From one and the same DNA sequence and, accordingly, one and the same pre-mRNA, several different mature mRNA molecules and, through their translation, several different polypeptides can be formed.

2 background

With alternative splicing it is only decided during the splicing process which DNA sequences are introns and which exons. The regulation probably takes place via pseudogenes.

The alternative splicing represents a particularly important evolution in the eukaryotes:

  • The information density of the DNA is considerably increased by superposition.
  • The formation of new proteins can take place much more easily than with prokaryotes, namely through a changed regulation of splicing.
  • The probability that a new protein created by alternative splicing is functional is higher than with a new protein created by mutating the coding DNA sequence. Every protein produced in this way during evolution contains at least several amino acid sequences that already function in other proteins.

Alternative splicing facilitates and accelerates the adaptation of eukaryotes to changed living conditions. This could have been a decisive step for the evolution of multicellular organisms with a longer generation duration. While with bacteria often less than an hour passes between two generations, this time with eukaryotes (e.g. humans) can grow to several decades. Without an appropriate mechanism for more efficient mutations, eukaryotes would hardly have been able to adapt to changed environmental conditions.

Alternative splicing is also important for understanding molecular genetics as a whole:

  • The discovery of alternative splicing means that the one-gene-one-enzyme hypothesis does not strictly apply to eukaryotes. A DNA sequence, i.e. a gene, can code for several different proteins.
  • Hereditary changes in the phenotype need not be due to a mutation of the coding DNA strand. They can also be caused by changes in the regulation of splicing.

see also:Gene, genetics

3 sources