C-terminus

Definition

The c-terminus refers to the end of a polypeptide or protein chain that has a free carboxyl group (-COOH). This structural feature is crucial in determining the overall shape and function of the protein, as it influences interactions with other molecules and the folding of the protein chain.

5 Must Know Facts For Your Next Test

1. The c-terminus of a protein influences how it interacts with other biomolecules, which can affect its functionality.
2. In protein synthesis, the c-terminus is formed during translation when the carboxyl group of the last amino acid in the chain remains unbound.
3. The c-terminus can be modified post-translationally, which may alter the protein's activity, stability, or localization within a cell.
4. Different proteins may have varying lengths of c-terminal tails that can contribute to their specific roles in cellular processes.
5. Proteins can have distinct c-terminal sequences that are critical for their proper localization and function within biological systems.

Review Questions

• How does the c-terminus contribute to the overall structure and function of proteins?
  • The c-terminus plays a vital role in determining a protein's structure and function by influencing its folding and interactions with other molecules. This end of the polypeptide chain contains a free carboxyl group that can engage in various biochemical interactions, including binding with ligands or participating in enzymatic activity. The specific sequence at the c-terminus can also dictate how proteins localize within cells, affecting their biological roles.
• Compare and contrast the c-terminus and N-terminus in terms of their roles in protein synthesis and structure.
  • The c-terminus and N-terminus are both critical to the structure of proteins, yet they serve different functions. The N-terminus, with its free amino group, is where translation begins, while the c-terminus concludes the polypeptide chain with a free carboxyl group. These termini influence not only how proteins are synthesized but also how they fold and interact with other molecules after synthesis. Their distinct properties affect overall protein stability, activity, and cellular localization.
• Evaluate how modifications at the c-terminus can impact protein functionality and interactions within biological systems.
  • Modifications at the c-terminus can significantly impact a protein's functionality and its interactions with other molecules. For example, adding phosphate groups through phosphorylation can activate or deactivate enzyme activity, while lipidation can target proteins to specific cellular membranes. Such post-translational modifications alter not just structural aspects but also functional pathways, influencing cellular processes like signaling, transport, and even apoptosis. Understanding these modifications helps elucidate complex biological systems and their regulatory mechanisms.

Related terms

N-terminus: The N-terminus is the start of a polypeptide chain, characterized by a free amino group (-NH2), and plays a significant role in protein synthesis and structure.

Peptide bond: A peptide bond is the covalent linkage formed between the carboxyl group of one amino acid and the amino group of another, resulting in the formation of a polypeptide.

Primary structure: The primary structure of a protein is the linear sequence of amino acids in a polypeptide chain, determined by the genetic code.