Signal Sequences

Signal sequences are short, several-nucleotide sequences with very specific information. They are very important for the function of nucleic acids.

Basic information
Break Down


 * the sequence marking the start of replication (in the D loop of mitochondrial DNA ),
 * sequences controlling transcription (located before, after or even inside the region they control).
 * Previously discovered, they were named after the discoverers Hogness  (eukaryote), Pribnow  (prokaryote), TATA box (allows transcription to start from adenine surrounded by a group of pyrimidine bases, located approx. 30 nucleotides after TATA in the direction from 5' to 3'). Adenine with a group of pyrimidine bases forms a so-called starting nucleotide (+1)

Functions


 * important for the formation of the mRNA cap (a sequence of 5 nucleotides after the starting nucleotide CATTC) and the signal for polyadenylation of the mRNA end AATAAA,
 * ensure the uncoupling and joining of DNA at predetermined locations,
 * they have the ability to change the spatial arrangement and apply their information content - so-called palindromes completely, incomplete palindromes (only partially complementary).

Moderately repetitive sequence
It is found singly or in groups scattered throughout the genome. They are transcribed into RNA, but their function is not yet precisely known.

They can be long or short. They contain Alu sequences in which there are restriction sites for the Alu I restriction enzyme.

A group of roughly 300,000–500,000 copies (5% of DNA) of sequences is found in a human haplotype. The mentioned sequences have a dimeric character, they contain two successively similar sequences.

Related Articles:

 * Signální sekvence polypeptidu, volné a vázané ribozómy
 * Regulace genové exprese u eukaryot
 * Regulace genové exprese u prokaryot
 * Transkripční faktory
 * Restriktázy

Reference:

 * 1) LIFTON, R P, M L GOLDBERG a R W KARP, et al. The organization of the histone genes in Drosophila melanogaster: functional and evolutionary implications. Cold Spring Harb Symp Quant Biol [online]. 1978, vol. 42 Pt 2, s. 1047-51, dostupné také z < https://www.ncbi.nlm.nih.gov/pubmed/98262 >. ISSN 0091-7451.
 * 2) ↑ PRIBNOW, D. Nucleotide sequence of an RNA polymerase binding site at an early T7 promoter. Proc Natl Acad Sci U S A [online]. 1975, vol. 72, no. 3, s. 784-8, dostupné také z < https://www.ncbi.nlm.nih.gov/pmc/articles/PMC432404/?tool=pubmed >. ISSN 0027-8424.
 * 3) OTOVA, Berta. Medical biology and genetics: 2nd volume. Prague 2008 edition. Karolinum Publishing House, 2008.  ISBN 978-80-246-1594-3