Laminins are cell
-
adhesive glycoproteins that are essential for basement membrane
assembly and function. Integrins are
important
laminin receptors, but their binding
site on the
heterotrimeric
laminin
s
is poorly defined structurally. We
report the
crystal
structure
at 2.13 Å resolution
of a minimal integrin
-
binding fragment of
mouse
laminin
-
111, consisting of ~50 resid
ues of
α
1
β
1
γ
1 coiled coil and the first three
lam
inin G
-
like (LG) domains of
the
α
1
chain
. The LG domains adopt a
triangular
arrangem
ent, with the C
-
terminus of the coiled coil situated between LG1 and LG2.
The critical integrin
-
binding
glutamic acid residue
in the
γ
1 chain tail is surface
-
exposed and
predicted
to bind to
the metal ion
-
dependent adhesion site in the integrin
β
1 subunit. Additional
contacts to the integrin
are likely to
be made by the
LG1 and
LG2 surfaces
adjacent to the
γ
1 chain tail, which are notably conserved and free of
obstructing glycans.