KKXX and for some proteins XKXX is a
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 ...
motif located in the C terminus in the
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
structure of a
protein
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, res ...
responsible for retrieval of
endoplasmic reticulum (ER) membrane proteins to and 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 cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ...
. These ER membrane proteins are transmembrane proteins that are then embedded into the ER membrane after transport from the Golgi. This motif is exclusively cytoplasmic and interacts with the
COPI protein complex to target the ER from the ''cis'' end of the Golgi apparatus by retrograde transport.
The abbreviation KKXX is formed by the corresponding
standard abbreviations for
lysine (K) and any
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
(X). This letter system was defined by the IUPAC and IUBMB in 1983, and is as follows:
*K—Lysine
*K—Lysine
*X— any amino acid
*X— any amino acid
See also
*
ER retention ER retention refers to proteins that are retained in the endoplasmic reticulum, or ER, after folding; these are known as ER resident proteins.
Protein localization to the ER often depends on certain sequences of amino acids located at the N termin ...
*
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 ...
*
COPI
*
Signal peptide
*
Protein targeting
References
Amino acids
Amino acid motifs
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