BIOINORGANIC CHEMISTRY A Short Course Second Edition

314 GROUP I AND II METALS IN BIOLOGICAL SYSTEMS: GROUP II

The peptides listed in Table 6.9 comprise the CaM - binding domains of

calmodulin target enzymes, many of which are large complex systems whose

activity is modulated by calmodulin binding. The names of some of these

enzymes appear in the calmodulin introductory section ( 6.3.2.1 ). Table 6.9 is

adapted from references 85 and 87 and uses the numbering systems found

therein. The newer and now more commonly used numbering system found

in reference 87 is shown in Table 6.9. The peptide sequences are aligned

based on the fi rst hydrophobic anchor residue, shown in bold type and dark

shading. Most often this peptide residue is a tryptophan, W (an amino acid

with a large aromatic side chain), that forms hydrophobic interactions with

the C - terminal domain of CaM. The second anchor residue, many times a

phenylalanine, F, also having a large aromatic side chain, is spaced some

number of residues further along the peptide chain (shown in bold with light

shading) and interacts with hydrophobic residues in CaM ’ s N - terminal

domain.

TABLE 6.9 Numbering System(s) for Calmodulin - Binding Peptides a

− 6 − 5 − 4 − 3 − 2 − 1 1 2 3

4

(1)b

5

(2)

6

(3)

7

(4)

8

(5)

skMLCK (M13)
(PDB: 2BBM)
1 – 14

K R R W K K N F

smMLCK (R20)
(PDB: 1CDL)
1 – 14

A R R K W Q K T G

CaMKII (PDB:
1CDM) 1 – 10

L K K F N A R R K L K G A I

CaMKI A K S K W K Q A F
C20W (PDB:
1CFF)

L R R G Q I L W F R G L

C24W Q I L W F R G L
C28W L R R G Q I L W F R G L
CaMKK α (rat)
(PDB: 1CKK)
1 – 16

V K L I P S W T T V I

CaMKK ( C.
elegans ) (PDB:
1IQ5)

V R V I P R L D T L I

MARCKS (PDB:
1IWQ)

K K R F S F K K S F K L S G

Source : Reference 85.
a Dark - shaded residues interact with calmodulin ’ s C - terminal domain. Light - shaded residues interact
with calmodulin ’ s N - terminal domain. For CaMKK peptides, the reverse is true.
b Numbers in parentheses correspond to reference 87.