SEC31B (SEC31 Homolog B, COPII Coat Complex Component): SEC31B is a protein that plays a crucial role in the COPII complex, which aids in transporting proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. It is vital for proper protein secretion and maintaining organelle integrity. Mutations in SEC31B can disrupt protein transport and contribute to disorders related to ER stress.