ER retention refers to
proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...
that are retained in the
endoplasmic reticulum
The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for ...
, or ER, after
folding; these are known as ER resident proteins.
Protein localization to the ER often depends on certain sequences of
amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...
located at the
N terminus
N, or n, is the fourteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages, and others worldwide. Its name in English is ''en'' (pronounced ), plural ''ens''.
History
...
or
C terminus. These sequences are known as
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 ...
s, molecular signatures, or sorting signals.
The classical ER retention signal is the C-terminal
KDEL sequence for lumen bound proteins and
KKXX (signal sequence is located in cytoplasm) for transmembrane localization. These signals allow for retrieval from the
Golgi apparatus
The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic Cell (biology), cells. Part of the endomembrane system in the cytoplasm, it protein targeting, packages proteins ...
by ER retention receptors, effectively maintaining the protein in the ER.
Other mechanisms for ER retention are being studied but are not as well characterized as signal retention.
ER retention receptor proteins
*
KDELR1
*
KDELR2
*
KDELR3
See also
*
KKXX (amino acid sequence) KKXX and for some proteins XKXX is a target peptide motif located in the C terminus in the amino acid structure of a protein responsible for retrieval of endoplasmic reticulum (ER) membrane proteins to and from the Golgi apparatus. These ER membran ...
*
KDEL (amino acid sequence)
KDEL is a target peptide sequence in mammals and plants located on the C-terminal end of the amino acid structure of a protein. The KDEL sequence prevents a protein from being secreted from the endoplasmic reticulum (ER) and facilitates its return ...
*
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 ...
*
Protein targeting
Protein targeting or protein sorting is the biological mechanism by which proteins are transported to their appropriate destinations within or outside the cell. Proteins can be targeted to the inner space of an organelle, different intracellular m ...
References
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