Final answer:
Integral membrane proteins typically have amphipathic, 20-25 amino acid long, α-helical transmembrane segments primarily composed of hydrophobic amino acids, with option 5 being correct, indicating all characteristics are typical.
Step-by-step explanation:
The characteristics of transmembrane segments of integral membrane proteins are essential for maintaining their stability and function in the cell membrane. The typical transmembrane segment is amphipathic, meaning it has both hydrophobic and hydrophilic parts, and is usually 20-25 amino acids in length. These segments are often α-helical in structure to span the hydrophobic interior of the membrane effectively.
Although transmembrane segments are primarily composed of hydrophobic amino acids, they can include hydrophilic amino acids if they interact within the protein structure and are shielded from the membrane's fatty acid environment. Therefore, all listed characteristics are typical of a transmembrane segment, making option 5 ('All are characteristics of a typical transmembrane segment') the correct choice.