Final answer:
The statement suggesting a strict odd-even alternation of start-transfer and stop-transfer signals in multipass transmembrane proteins is False. Start-transfer sequences initiate membrane integration, while hydrophobic stop-transfer sequences anchor the protein within the membrane, without a strict odd-even rule.
Step-by-step explanation:
The statement that in multipass transmembrane proteins, the odd-numbered transmembrane segments act as start-transfer signals and the even-numbered segments act as stop-transfer signals is False. The synthesis of membrane-spanning proteins is a complex process where the signal sequence at the N-terminus is crucial for initiating the integration of the protein into the membrane of the rough endoplasmic reticulum (RER).
However, the alternating start-transfer and stop-transfer sequence model this statement suggests is not accurate. In reality, the start-transfer sequences guide the insertion into the membrane and then subsequent stop-transfer sequences, which are hydrophobic amino acid sequences within the polypeptide, help anchor the protein in the membrane. This does not strictly alternate between odd and even transmembrane segments. Multiple stop-transfer sequences can cause the protein to span the membrane multiple times, but these sequences are not obligatorily linked to an odd-even positioning from the N-terminus.