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PDBsum entry 1mvv
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References listed in PDB file
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Key reference
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Title
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Role of n-Linked oligosaccharide flexibility in mannose phosphorylation of lysosomal enzyme cathepsin l.
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Authors
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J.B.Warner,
C.Thalhauser,
K.Tao,
G.G.Sahagian.
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Ref.
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J Biol Chem, 2002,
277,
41897-41905.
[DOI no: ]
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PubMed id
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Abstract
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Mannose phosphorylation of N-linked oligosaccharides by UDP-GlcNAc:lysosomal
enzyme N-acetylglucosamine-1-phosphotransferase is a key step in the targeting
of lysosomal enzymes in mammalian cells and tissues. The selectivity of this
process is determined by lysine-based phosphorylation signals shared by
lysosomal enzymes of diverse structure and function. By introducing new
glycosylation sites at several locations on the surface of mouse procathepsin L
and modeling oligosaccharide conformations for sites that are phosphorylated, it
was shown that the inherent flexibility of N-linked oligosaccharides can account
for the specificity of the transferase for oligosaccharides at different
locations on the protein. By using this approach, the physical relationship
between the lysine-based signal and the site of phosphorylation of mannose
residues was determined. The analysis also revealed the existence of additional
independent lysine-based phosphorylation signals on procathepsin L, which
account for the low level of phosphorylation observed when the primary
Lys-54/Lys-99 signal is ablated. Mutagenesis of residues that surround Lys-54
and Lys-99 and demonstration of mannose phosphorylation of a glycosylated
derivative of green fluorescent protein provide strong evidence that the
cathepsin L phosphorylation signal is a simple structure composed of as few as
two well placed lysine residues.
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Figure 5.
Fig. 5. Location of the new glycosylation sites on
cathepsin L. The wild-type glycosylation site (Asn-221) is shown
in blue. The glycosylation sites that were added but were not
significantly phosphorylated are shown in red. Glycosylation
sites that are highly phosphorylated are shown in green. The
 -carbons of
the critical lysines, Lys-54 and Lys-99, are shown in yellow.
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Figure 6.
Fig. 6. Modeling of oligosaccharide clouds on cathepsin
L. Modeled structures for oligosaccharide clouds of highly
phosphorylated cathepsin L constructs are shown along with an
overlay and overlap images. The overlap image is a superposition
of the six individual structures. The overlap image shows the
oligosaccharide region shared by the six individual structures.
Oligosaccharide clouds were modeled as described under
"Experimental Procedures." The -carbons of
critical lysine residues Lys-54 and Lys-99 are displayed in
white. WT, wild type.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2002,
277,
41897-41905)
copyright 2002.
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