Molecular mechanism of ceramide trafficking from the endoplasmic reticulum to the golgi apparatus in mammalian cells

Abstract

Synthesis and sorting of lipids are essential events for membrane biogenesis and its homeostasis. The endoplasmic reticulum (ER) is the center of the de novo synthesis of various lipid types. Trafficking of various lipids from the ER to other organelles has been suggested to occur by mechanisms different from the vesicle-mediated mechanism for protein trafficking. However, molecular mechanisms underlying intracellular trafficking of lipids remain poorly understood. Ceramide is synthesised at the ER, and translocated to the Golgi compartment for conversion to sphingomyelin (SM). We previously isolated a mammalian cultured cell mutant defective in ceramide trafficking, and have recently identified a key factor (named CERT) for ceramide trafficking in functional rescue experiments and proposed a molecular lipid extraction and transfer model for the non-vesicular mechanism of CERT-mediated trafficking of ceramide. © Springer-Verlag Tokyo 2006. All rights reserved.