The multiple activities of CtBP/BARS proteins: the Golgi view

The C terminal-binding protein (CtBP) family functions in the nucleus as co-repressors of transcription and has a crucial role in differentiation, apoptosis, oncogenesis and development. Recently, the products of the CtBP1 gene have been implicated in important cytoplasmic functions, including membrane fission in intracellular trafficking, the partitioning of the Golgi complex during mitosis and the organization of ribbon synapses. This has led to a redefinition of the CtBPs as multifunctional proteins. Shuttling of CtBPs between the nucleus and the cytoplasm can be finely regulated by post-translational modifications. In addition, the structural homology with the dehydrogenase family of proteins and the ability of CtBPs to bind NAD(+) and acyl-CoAs have offered clues to the molecular mechanisms that enable these proteins to have different functions. Here, we discuss the cytoplasmic roles of the CtBPs and the possible mechanisms that enable them to switch between cell compartments and multiple functions.