Open reading frame

An Open Reading Frame (ORF) is a sequence of DNA or RNA that has the potential to be translated into a protein. The sequence starts with a start codon (ATG in DNA or AUG in RNA) and ends with one of the three stop codons (TAA, TAG, or TGA in DNA; UAA, UAG, or UGA in RNA).

Definition

In molecular genetics, an ORF is a stretch of the DNA sequence that is transcribed into RNA and translated into a protein. The ORF contains the information to make a protein product, and it is the part of the gene that is translated.

Identification

ORFs are identified by scanning the genome for specific sequences that indicate the start and stop of genes. The start codon, usually AUG (or ATG in DNA), signifies the start of the ORF. The sequence continues until a stop codon (UAA, UAG, or UGA in RNA; TAA, TAG, or TGA in DNA) is encountered.

Function

The function of the protein encoded by an ORF can often be predicted by comparing the predicted amino acid sequence to those of known proteins in other organisms. In this way, ORFs are used to identify potential protein-coding genes within a sequence of DNA.

See also

• Gene
• Protein biosynthesis
• Genetic code
• Transcription (genetics)
• Translation (biology)

References

• Open reading frame
  Open reading frame
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  Open reading frame