Which of the following is a key characteristic of a nuclear export signal (NES)?

A nuclear export signal (NES) is crucial in the process of guiding proteins out of the nucleus and into the cytoplasm. The key characteristic of a NES is that it typically consists of hydrophobic amino acids. This hydrophobicity is essential because it allows the NES to interact with specific export receptors, known as exportins, which are required for the transport of proteins through the nuclear pore complex.

The hydrophobic amino acids in the NES facilitate these interactions by inserting themselves into the hydrophobic pockets of exportins, enhancing the binding affinity. This is significant as it ensures efficient recognition and transport of the protein, thus playing a vital role in nuclear-cytoplasmic trafficking.

Understanding the structure and composition of a NES helps explain its function in cellular processes such as gene expression, signaling, and protein processing, where timely export from the nucleus is critical.