The amphiphysin family of proteins and their role in endocytosis at the synapse

Clathrin-mediated endocytosis at the plasma membrane is a major pathway of synaptic vesicle recycling in neurones, but little is known about the molecular machinery that orchestrates the process. The amphiphysin protein has recently emerged into the limelight since its discovery in 1992 as a synaptic vesicle-associated protein. It was subsequently found to interact in vitro with the GTPase dynamin through its SH3 domain. However, only in the past year has its role in endocytosis been confirmed, with the demonstration that the introduction of dominant-negative-acting SH3 domains into living cells causes a potent blockade of clathrin-mediated endocytosis. This, together with the discovery by several groups of a second nerve terminal-enriched amphiphysin isoform, and the finding that the two proteins heterodimerize, further suggests that the amphiphysins are closely connected with dynamin-mediated vesicle budding. This review summarizes current views in the field, and draws on data that suggest intriguing alternative roles--including possible involvement in the cytoskeleton and in tumour suppression--for certain members of the amphiphysin family.