Reticuloplasmins: a novel group of proteins in the endoplasmic reticulum

The existence of a special milieu within the endoplasmic reticulum (ER) has been well known to microscopists because of its special osmiphilic properties and the term ‘reticuloplasm’ was coined to describe the contents of the ER (Krstic, 1979). The purpose of this article is to bring together some recent observations showing that reticuloplasm does indeed contain a very special complement of its own resident proteins, referred to as reticuloplasmins, and to consider the possible role of these proteins in ER structure and function.