It has become increasingly clear during the last few years that
metabolic processes in plant, bacterial, and mammalian cells can no
longer be thought of as taking place in a homogeneous intracellular
phase. Many enzymes and blood group and histocompatibility antigens have
been found associated with subcellular organelles; some chemotherapeutic
agents are active because they interfere with the biosynthesis of
membranes, and studies of hormonal regulation involve investigations of
various aspects of membrane function. The integration of structure and
function has become one of the most exciting areas of biochemical
investigation, e.g., the brilliant investigations correlating the
mechanisms of bioenergetics with the structure of the mitochondrion and
the biochemical understanding of the 'p-galactoside permease in Es-
cherichia coli as it relates to transport phenomena across the cell
surface membrane. Many other intracellular processes are being defined
as membrane- associated phen