Intracellular Membrane Fusion
Dalu Xu and Jesse C. Hay
Fusion of biological membranes plays an important role in cell structure and function. It is essential for organelle biogenesis, vesicle targeting, constitutive and regulated exocytosis, endocytosis, pathogen invasion of host cells, sperm-egg fusion and skeletal muscle formation. This chapter summarizes our current knowledge of the mechanisms of intracellular membrane fusion with particular emphasis on the structure, function and regulation of the N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein family. The chapter provides details of current ideas on SNARE mechanisms of action in membrane fusion and the conserved features of SNARE complexes. Also covered in detail are SNARE regulation; by lipids, SNARE amino-terminal (NT) domains, posttranslational modifications, SM proteins, tethering proteins, calcium and other regulators. Fusion mechanisms employed by enveloped viruses are also summarized to provide a broader perspective.