UNDERSTANDING CELL SECRETION AND MEMBRANE FUSION PROCESSES ON THE NANOSCALE USING THE ATOMIC FORCE MICROSCOPE - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 98

Chapter 5

UNDERSTANDING CELL SECRETION AND
MEMBRANE FUSION PROCESSES ON THE
NANOSCALE USING THE ATOMIC FORCE
MICROSCOPE

Bhanu P. Jena
Department of Physiology, Wayne State University School of Medicine,
5245 Scott Hall, Detroit, MI 48201, USA
[e-mail]

5.1 ATOMIC FORCE MICROSCOPY: RESOLVING A MAJOR
CONUNDRUM IN CELL SECRETION

Secretion is a fundamental cellular process as old as life itself and occurs in
all living organisms, from the simple yeast to cells in humans. Secretion is
responsible for a variety of physiological activities in living organisms, such
as neurotransmission and the release of hormones and digestive enzymes.
Secretory defects in cells are responsible for a host of debilitating diseases.
Since the mid 1950s, it was believed that during cell secretion, secretory
vesicles completely merge at the cell plasma membrane, resulting in the
diffusion of intravesicular contents to the cell exterior and the compensatory
retrieval of the excess membrane by endocytosis. In contrast, the observation
of partially empty vesicles in cells following secretion could not be justiied
according to the aforementioned mechanism. Then in the 1960s, experimental
data concerning neurotransmitter release mechanisms by Katz

1

and Folkow

et al. 2 brilliantly hypothesized that limitation of the quantal packet may
be set by the nerve membrane, in which case the size of the packet may