This volume focuses exclusively on those endocytic processes that sequester proteins by a selective, receptor-mediated mechanism. In such an endocytic process, cell surface receptors specifically bind protein ligands and localize them to specialized invaginations of the plasma membrane. These regions are coated pits, so named because they are lined on the cytoplasmic face with an ordered array of the protein, clathrin. It is this 'coat' which provides their characteristic electron microscopic image. Subsequently, these regions pinch off to form coated vesicles which rapidly lose their 'coat'...

This new se ries is concerned with intercellular communication and recognition. It is now widely appreciated that these processes playa crucial role in virtually all biological systems and functions. These encompass fertilisation, embryonic development, infectious interactions, the activity of the nervous system, the regulation of growth and develop ment by hormones and the immune response to foreign or 'non-self antigens. Historically as described in the first review in this volume, the general concept of cell-associated receptors as the molecular entity primarily responsible for the...