A topogenic sequence is a collective term used for a
peptide sequence
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
A ...
present at nascent proteins essential for their insertion and orienting in
cellular membranes. The sequences are also used to translocate proteins across various intracellular membranes,
and ensure they are transported to the correct organelle after synthesis.
The position of the sequence may be at the end, e.g. N-terminal signal sequence, or in mid parts of the nascent protein, e.g. stop-transfer anchor sequences and signal-anchor sequences.
If the sequence is at the end of the polypeptide, it is cleaved off after entering the ER-lumen (via a translocon) by a signal peptidase, and subsequently degraded.
As an example, the vast majority of all known complex plastid
preproteins (an 'unactivated' protein) encoded in the nucleus possess a topogenic sequence.
See also
*
Protein targeting
:''This article deals with protein targeting in eukaryotes unless specified otherwise.''
Protein targeting or protein sorting is the biological mechanism by which proteins are transported to their appropriate destinations within or outside the ce ...
*
Target peptide
Target may refer to:
Physical items
* Shooting target, used in marksmanship training and various shooting sports
** Bullseye (target), the goal one for which one aims in many of these sports
** Aiming point, in field artillery, fi ...
*
Translocon The translocon (also known as a translocator or translocation channel) is a complex of proteins associated with the translocation of polypeptides across membranes. In eukaryotes the term translocon most commonly refers to the complex that transport ...
*
Signal peptide
A signal peptide (sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence or leader peptide) is a short peptide (usually 16-30 amino acids long) present at the N-ter ...
References
Peptide sequences
{{Biochem-stub