IMGT®, the international ImMunoGeneTics information system®

DNA strand orientation

The DNA strand orientation is by convention 5' → 3'.

This concept allows to determine, for a given gene, the gene orientation relative to the 5' → 3' DNA strand.

• sense: same direction
• antisense: opposite direction

This concept is particulary important when a same sequence contains genes with different orientations.

The 'DNA strand orientation' concept is part of the 'ORIENTATION' axiom of IMGT-ONTOLOGY [1].

The two concept instances are exclusive:

• - 'Sense', 'Plus' or 'Coding' strand
  The 5'->3' DNA strand is designated, for a given gene, as 'sense', 'plus' or 'coding' strand because its sequence is identical to the sequence of the premessenger (premRNA) [except for uracile (U) in RNA, instead of thymine (T) in DNA]. This coding strand is not transcribed.
• - 'Antisense', 'Minus' or 'Not coding' strand
  The complementary 3'->5' strand which is the strand transcribed by the RNA polymerase is designated as "template" DNA (matrice in French). This strand is also described as 'antisense', 'minus' or 'not coding'. It is complementary to the 5'->3' strand.
  In databases, the corresponding sequence, for a given gene, is designated as 'complement'. It is possible to convert the sequence to the 'sense' orientation using tools such as 'reverse-complement'.