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.

Links

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