Figure 2.
Fig. 2. The structure of CALM-N bound to PtdIns(4,5)P[2]. (A)
Ribbon diagram of CALM-N, colored from green at the
NH[2]-terminus to gold at the COOH-terminus. (B) The ENTH domain
of epsin in the same orientation [PDB code 1edu (23)]. (C) The
surface of CALM-N colored by electrostatic potential, red +10 kT
e^ 1,
blue -10 kT e^ 1.
This is a slightly different view from that in (A), to show the
strong positive patch that binds PtdIns(4,5)P[2]. (D) Close-up
of PtdIns(4,5)P[2]-binding site, showing a difference electron
density map omitting the ligand, contoured at 2 . There
was strong density only for the 4- and 5-phosphates, weak
density for the inositol ring and the 1-phosphate, and none for
the lipid chains. (E) Ins(4,5)P[2] also shows most density for
the phosphates: it was modeled as a 50:50 mixture of two binding
modes interchanging the 4- and 5-phosphates. (F) InsP[6] was
probably bound in multiple orientations, and the orientation of
the inositol ring was different from that of the bisphosphates.
(G) Sequence alignments of the very similar CALM-N and AP180-N
(81% identical, unshaded, further conserved residues shaded
mauve), and the structurally similar epsin ENTH domain (16%
sequence identity, shaded orange). Helices
are shown as cylinders, colored as in A and B.
PtdIns(4,5)P[2]-binding residues are marked with arrows. Also
shown is the PtdIns(4,5)P[2]-binding region of -adaptin,
with the conserved PtdIns(4,5)P[2]-binding motif and predicted
helices.
(H) The 1 to 2 loop
regions for three families of proteins: AP180/CALM family with
the PtdIns(4,5)P[2]-binding motif (blue); some other proteins
with the PtdIns(4,5)P[2]-binding motif (blue); epsin family with
the (D/E)PW motif (orange). Other conserved residues are colored
purple. Yeast-SLA2 is Yeast-SLA2p.
The above figure is reprinted
by permission from the AAAs:
Science
(2001,
291,
1051-1055)
copyright 2001.
1,
blue -10 kT e^ 
. There
was strong density only for the 4- and 5-phosphates, weak
density for the inositol ring and the 1-phosphate, and none for
the lipid chains. (E) Ins(4,5)P[2] also shows most density for
the phosphates: it was modeled as a 50:50 mixture of two binding
modes interchanging the 4- and 5-phosphates. (F) InsP[6] was
probably bound in multiple orientations, and the orientation of
the inositol ring was different from that of the bisphosphates.
(G) Sequence alignments of the very similar CALM-N and AP180-N
(81% identical, unshaded, further conserved residues shaded
mauve), and the structurally similar epsin ENTH domain (16%
sequence identity, shaded orange). 
Helices
are shown as cylinders, colored as in A and B.
PtdIns(4,5)P[2]-binding residues are marked with arrows. Also
shown is the PtdIns(4,5)P[2]-binding region of