The present volume of Current Topics in Microbiology and Immunology contains
seven chapters that illuminate various aspects of a protein’s genesis and
terminal fate in the endoplasmic reticulum (ER). This area is of immediate
medical relevance and has blossomed, to no small extent, because of the study
of molecules central to the function of the immune system [immunoglobulins,
T cell receptors, major histocompatibility complex (MHC)-encoded
products]. Similarly, the clever strategies used by bacteria or viruses to gain
a foothold in the host and ensure their continued survival have uncovered
altogether new cell biological principles. It is therefore fitting that a special
volume be devoted to the interplay between pathways of protein degradation
in the ER and a wide variety of pathogens. The concept of quality control
emerged with the appreciation that, in the case of multimeric glycoproteins,
any unpaired glycoprotein subunit had great difficulties leaving its site of
synthesis—the ER—and was destroyed instead. Free immunoglobulin heavy
chains were probably the earliest documented example of this kind, and were
long known to cause pathology when their accumulation went unchecked