 |
PDBsum entry 3es6
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Cell adhesion
|
PDB id
|
|
|
|
3es6
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Crystal structure of the novel complex formed between zinc alpha2-Glycoprotein (zag) and prolactin-Inducible protein (pip) from human seminal plasma.
|
|
|
Authors
|
|
M.I.Hassan,
S.Bilgrami,
V.Kumar,
N.Singh,
S.Yadav,
P.Kaur,
T.P.Singh.
|
|
|
Ref.
|
|
J Mol Biol, 2008,
384,
663-672.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
|
|
|
Abstract
|
|
|
This is the first report on the formation of a complex between zinc
alpha2-glycoprotein (ZAG) and prolactin-inducible protein (PIP). The complex was
purified from human seminal plasma and crystallized using 20% polyethylene
glycol 9000 and 5% hexaethylene glycol. The structure of the complex has been
determined using X-ray crystallographic method and refined to an R(cryst) of
0.199 (R(free)=0.239). The structure of ZAG is broadly similar to the structure
of serum ZAG. The scaffolding of PIP consists of seven beta-strands that are
organized in the form of two antiparallel beta-pleated sheets, resulting in the
formation of a sandwiched beta-sheet. The amino acid sequence of PIP contains
one potential N-glycosylation site at Asn77, and the same is found glycosylated
with four sugar residues. The structure of the complex shows that the
beta-structure of PIP is ideally aligned with the beta-structure of domain
alpha3 of ZAG to form a long interface between two proteins. The proximal
beta-strands at the long interface are arranged in an antiparallel manner. There
are 12 hydrogen bonds and three salt bridges between ZAG and PIP. At the two
ends of vertical interface, two salt bridges are formed between pairs of
Lys41-Asp233 and Lys68-Glu229. On the perpendicular interface involving
alpha1-alpha2 domains of ZAG and a loop of PIP, another salt bridge is formed.
The internal space at the corner of the L-shaped structure is filled with
solvent molecules including a carbonate ion. The overall buried area in the
complex is approximately 914 A(2), which is considerably higher than the 660
A(2) reported for the class I major histocompatibility complex structures.
|
|
|
|
|
|
|
|
Figure 2.
Fig. 2. (a) Schematic representation of PIP.^46 (b) A cluster
of hydrophobic residues present between two β-sheets of PIP.
The interactions of the glycan chain residue NAG with protein
residues are shown in ball-and-stick representation. The
hydrogen bonds are presented in dotted line. (c) The
superimposition of C^α traces of PIP (green) and FN-7 (magenta)
is shown. The comparisons of loops L4 and L7 (blue) are
significantly different.
|
|
Figure 5.
Fig. 5. The electron density for the PIP was observed in the
cleft of domains α1–α2 and α3 of ZAG.
|
|
|
|
|
|
The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2008,
384,
663-672)
copyright 2008.
|
|
|
|
|
|
|
