SEC31B (SEC31 Homolog B, COPII Coat Complex Component): SEC31B is a protein that serves as a crucial part of the COPII complex, which enables the transport of proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. It plays an essential role in proper protein secretion and the preservation of organelle integrity. Mutations in SEC31B can disrupt protein transport and contribute to disorders related to ER stress.