Biology Reference
In-Depth Information
Chapter 4
Pericellular Proteolysis
Judith S. Bond, Timothy R. Keiffer, and Qi Sun
Abstract The immediate environment of cells is a rich source of proteolytic
enzymes due to plasma membrane and secreted proteases, and many important
physiological and pathological processes take place pericellularly. Meprin metal-
loproteases that are membrane-bound and secreted act pericellularly to modify
proteins and peptides, and there is increasing evidence that these modifications
have important implications in the hematological and immune systems.
4.1
Introduction
“Pericellular proteolysis” is proteolytic degradation surrounding a cell. This can
occur as a consequence of the action of plasma membrane proteases or proteases
secreted from cells that act in the immediate environment of the cell. There are
numerous examples of proteases that engage in pericellular proteolysis (including
serine, cysteine, and aspartic and metalloproteases); metalloproteases are one of the
major classes that act in the environment surrounding cells. The plasma membrane is
a rich source of proteases, and well-studied examples include angiotensin-
converting enzyme (ACE), tumor necrosis
converting enzyme (TACE), mem-
brane-type matrix metalloproteinases (MT-MMPs), and meprins (Fig. 4.1 ). These
enzymes may be quite selective for substrates (e.g., ACE) or nonspecific for sub-
strates (e.g., meprins), but their action is limited by their location under normal
conditions (at specific plasma membranes or in polarized cells at specific parts of the
membrane, e.g., apical or basement membrane). There are also numerous examples
of secreted proteases that act pericellularly, including collagen-processing enzymes
a
J.S. Bond ( * ) and T.R. Keiffer
Department of Biochemistry and Molecular Biology, The Pennsylvania State University College
of Medicine, Hershey, PA 17033, USA
e-mail: jbond@psu.edu
Q. Sun
Department of Pediatrics, The Pennsylvania State University College of Medicine, Hershey,
PA 17033, USA
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