C-terminal

C-terminal

The C-terminal (also known as the carboxyl-terminus, C-terminus, or COOH-terminus) is the end of an amino acid chain, which is terminated by a free carboxyl group (-COOH). In the context of proteins, the C-terminal is the end of the amino acid sequence that is synthesized last during translation.

Structure and Function

Proteins are synthesized from the N-terminal to the C-terminal. The C-terminal is crucial for the function and stability of proteins. It often contains specific sequences that are recognized by other molecules, which can influence the protein's localization, stability, and interaction with other proteins.

Post-translational Modifications

The C-terminal can undergo various post-translational modifications, which can affect the protein's function. Common modifications include:

• Amidation: The conversion of the carboxyl group into an amide group, which can affect the protein's stability and activity.
• Prenylation: The addition of lipid groups, which can anchor proteins to cell membranes.
• Ubiquitination: The attachment of ubiquitin molecules, marking the protein for degradation by the proteasome.

Biological Significance

The C-terminal plays a critical role in the targeting of proteins to specific cellular compartments. For example, many proteins destined for the endoplasmic reticulum have a C-terminal KDEL sequence that is recognized by specific receptors.

C-terminal Domains

Some proteins have distinct C-terminal domains that are essential for their function. For instance, the C-terminal domain of RNA polymerase II is involved in the regulation of gene expression.

Clinical Relevance

Mutations or alterations in the C-terminal region of proteins can lead to various diseases. For example, mutations in the C-terminal of the CFTR protein are associated with cystic fibrosis.

Research Techniques

Several techniques are used to study the C-terminal of proteins, including:

• Mass spectrometry: Used to identify and characterize post-translational modifications.
• Western blotting: Utilizes antibodies specific to the C-terminal region to detect proteins.
• Site-directed mutagenesis: Allows researchers to study the effects of specific mutations in the C-terminal region.

See Also

• N-terminal
• Protein structure
• Amino acid sequence

External Links

• National Center for Biotechnology Information
• UniProt