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Figure 4.
Figure 4: A new CaM-binding motif that interacts strongly with
4Ca^2+-CaM. a, The overall conformation and polarity of the
insert-2 -CaM complex (new 1-6-14 motif) is compared with those
observed when CaM interacts with myosin light chain kinase
(MLCK) (classic 1-8-14 motif) (target peptides superimposed).
Note that in both cases the C-lobe of CaM in an open
conformation grips the N-terminal region of the target sequence,
largely through the first anchoring hydrophobic residue
(W793/W800). b, In contrast, comparison of the N-lobes (helices
A and D superimposed) shows differences in their conformation
(closure differs by 20°) and in the target peptide position
(note the 14th anchoring residue position) within the lobe. Note
that the sixth anchoring residue of the 1-6-14 motif (W798)
interacts strongly with both lobes of CaM (helices A and H). c,
Sequence comparison of the two CaM-binding motifs. The letters
n, c and b indicate whether each residue of these motifs
interacts with the N-lobe, the C-lobe or both lobes of CaM,
respectively.
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