C-terminus

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C-terminal
)
A tetrapeptide (example: Val-Gly-Ser-Ala) with green highlighted N-terminal α-amino acid (example: L-valine) and blue marked C-terminal α-amino acid (example: L-alanine).

The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, carboxy tail, C-terminal end, or COOH-terminus) is the end of an

carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus
to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus.

Chemistry

Each amino acid has a carboxyl group and an

N-terminus
. Proteins are naturally synthesized starting from the N-terminus and ending at the C-terminus.

Function

C-terminal retention signals

While the

secretory pathway
.

Peroxisomal targeting signal

The sequence -SKL (Ser-Lys-Leu) or similar near C-terminus serves as peroxisomal targeting signal 1, directing the protein into peroxisome.

C-terminal modifications

The C-terminus of proteins can be modified

posttranslationally, most commonly by the addition of a lipid anchor to the C-terminus that allows the protein to be inserted into a membrane without having a transmembrane domain
.

Prenylation

One form of C-terminal modification is prenylation. During prenylation, a farnesyl- or geranylgeranyl-isoprenoid membrane anchor is added to a cysteine residue near the C-terminus. Small, membrane-bound G proteins are often modified this way.

GPI anchors

Another form of C-terminal modification is the addition of a phosphoglycan, glycosylphosphatidylinositol (GPI), as a membrane anchor. The GPI anchor is attached to the C-terminus after proteolytic cleavage of a C-terminal propeptide. The most prominent example for this type of modification is the prion protein.

Methylation

C-terminal

methyl ester.[1]

C-terminal domain

RNA POL II in action.

The C-terminal domain of some proteins has specialized functions. In humans, the CTD of

initiation of DNA transcription, the capping of the RNA transcript, and attachment to the spliceosome for RNA splicing.[3]

See also

  • N-terminus
  • TopFIND, a scientific database covering proteases, their cleavage site specificity, substrates, inhibitors and protein termini originating from their activity

References

  1. ^ "RHEA:48544". Swiss Institute of Bioinformatics.
  2. S2CID 4418258
    .
  3. .