Final answer:
Sec23 acts as a GAP for Sar1 to trigger COPII coat disassembly, while Sec24 is involved in cargo selection during vesicle formation in eukaryotic cells. The coordinated roles of these proteins ensure proper coat removal and vesicle delivery to the Golgi apparatus.
Step-by-step explanation:
The role of Sec23 and Sec24 proteins is essential in the process of vesicular trafficking within eukaryotic cells, particularly during the coat removal stage of vesicle formation. In the secretory pathway, these proteins are part of the COPII coat complex that mediates the budding of vesicles from the endoplasmic reticulum (ER). Sec23 acts as a GTPase-activating protein (GAP) for Sar1, a GTPase responsible for COPII coat assembly and disassembly. When Sar1 hydrolyzes GTP to GDP, this triggers the disassociation of the COPII coat, including Sec23 and Sec24, allowing the vesicle to move towards the Golgi apparatus.
On the other hand, Sec24 functions as a cargo-binding subunit, recognizing and selectively encapsulating cargo proteins into the transport vesicles. After the budding process, the hydrolysis of GTP on Sar1, facilitated by Sec23, eventually leads to the coat removal, enabling the vesicle to fuse with the target membrane. This regulated detachment is crucial as it prevents premature uncoating and ensures that vesicles reach their destination with their cargo intact.