In molecular genetics

Molecular genetics

Molecular genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level. The field studies how the genes are transferred from generation to generation. Molecular genetics employs the methods of genetics and molecular biology...

, the three prime untranslated region (3' UTR) is a particular section of messenger RNA

Messenger RNA

Messenger RNA is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein...

 (mRNA). It is preceeded by the coding region

Coding region

The coding region of a gene, also known as the coding sequence or CDS, is that portion of a gene's DNA or RNA, composed of exons, that codes for protein. The region is bounded nearer the 5' end by a start codon and nearer the 3' end with a stop codon...

.

An mRNA molecule codes for a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 through translation

Translation (genetics)

In molecular biology and genetics, translation is the third stage of protein biosynthesis . In translation, messenger RNA produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein...

. The mRNA also contains regions that are not translated. In eukaryotes these regions are the cap

5' cap

The 5' cap is a specially altered nucleotide on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. The process of 5' capping is vital to creating mature messenger RNA, which is then able to undergo translation...

, 5' untranslated region, 3' untranslated region, and polyA tail

Polyadenylation

Polyadenylation is the addition of a poly tail to an RNA molecule. The poly tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA for translation...

 (see diagram).

In prokaryotes mRNA structures have some differences (see mRNA) as do histone

Histone

In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...

 mRNAs. However, both have 3' UTRs.

Several regulatory sequence

Regulatory sequence

A regulatory sequence is a segment of DNA where regulatory proteins such as transcription factors bind preferentially. These regulatory proteins bind to short stretches of DNA called regulatory regions, which are appropriately positioned in the genome, usually a short distance 'upstream' of the...

s are found in the 3' UTR:

• A polyadenylation
  Polyadenylation
  Polyadenylation is the addition of a poly tail to an RNA molecule. The poly tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA for translation...
  
   signal, usually AAUAAA, or a slight variant. This marks the site of cleavage of the transcript approximately 30 base pair
  Base pair
  In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
  
  s past the signal, followed by the addition of several hundred adenine residues (poly-A tail).
• Binding sites for proteins, that may affect the mRNA's stability or location in the cell, like SECIS element
  SECIS element
  In biology, the SECIS element is an RNA element around 60 nucleotides in length that adopts a stem-loop structure. This structural motif directs the cell to translate UGA codons as selenocysteines...
  
  s (which direct the ribosome to translate the codon UGA as selenocysteine
  Selenocysteine
  Selenocysteine is an amino acid that is present in several enzymes .-Nomenclature:...
  
  s rather than as a stop codon), or AU-rich element
  AU-rich element
  AU-rich elements are one of the most common types of regulatory elements found in mRNAs. They are involved in the control of gene expression. They are the most common determinant of RNA stability in mammalian cells....
  
  s (AREs), stretches consisting of mainly adenine
  Adenine
  Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
  
   and uracil
  Uracil
  Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...
  
   nucleotides (which can either stabilize or destabilize the mRNA depending on the protein bound to it).
• Binding sites for miRNA
  Mirna
  Mirna may refer to:geographical entities* Mirna , a river in Istria, Croatia* Mirna , a river in Slovenia, tributary of the river Sava* Mirna , a settlement in the municipality of Mirna in Southeastern Sloveniapeople...
  
  s, a type of RNAi
  RNAI
  RNAI is a non-coding RNA that is an antisense repressor of the replication of some E. coli plasmids, including ColE1. Plasmid replication is usually initiated by RNAII, which acts as a primer by binding to its template DNA. The complementary RNAI binds RNAII prohibiting it from its initiation role...
  
  .

External links

• Brief introduction to mRNA regulatory elements
• UTResource 3' UTR analysis
• UTRome.org 3' UTRs in nematodes
• Medical Subject Heading: 3' Untranslated Regions