ERGIC53

ERGIC53, also known as LMAN1, is a type I transmembrane protein that plays a crucial role in the secretory and endoplasmic reticulum-Golgi intermediate compartment (ERGIC) transport pathway. It is a type II lectin, meaning it binds to carbohydrates. ERGIC53 is primarily found in the ERGIC and the cis-Golgi network. Its main function is to act as a cargo receptor, recognizing and binding to specific proteins, particularly those destined for secretion or insertion into the plasma membrane.

This binding activity is essential for the proper sorting and trafficking of these proteins from the endoplasmic reticulum to the Golgi apparatus and then to their final destinations. ERGIC53 facilitates the retrieval of escaped ER-resident proteins back to the ER, thus maintaining protein homeostasis. Mutations in the LMAN1 gene, which encodes ERGIC53, have been linked to certain genetic disorders, including Factor V and Factor VIII deficiency type 1, a bleeding disorder characterized by reduced levels of coagulation factors V and VIII. This highlights the critical role of ERGIC53 in the proper maturation and secretion of these essential proteins. The protein's interaction with other cellular components, such as COPII coat proteins, is also vital for efficient vesicle budding and transport.