9MXD: Human E104A calmodulin:MLCK RM20 complex

Human E104A calmodulin:MLCK RM20 complex. Determined by X-ray diffraction at 1.17 Å resolution. Released 11 Feb 2026.

Method: X-ray diffraction
Resolution: 1.17 Å
Organism: Homo sapiens
Chains: 2
Atoms: 1,552
Mol. weight: 19.28 kDa
Ligands: CA
Released: 11 Feb 2026

Explore 9MXD in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9MXD contains 9 α-helices and 4 β-strands across 2 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 8 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	6-19	14
β-strand	26-27	2	1
α-helix	29-38	10
α-helix	45-53	9
β-strand	63-64	2	1
α-helix	65-73	9
α-helix	82-92	11
β-strand	99-100	2	2
α-helix	102-111	10
α-helix	118-128	11
β-strand	136-137	2	2
α-helix	138-146	9

Chain B: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	5-19	15

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Calmodulin-1	A	protein	149	Homo sapiens	P0DP23 (AlphaFold model)
Myosin light chain kinase, smooth muscle, deglutamylated form	B	protein	20	Homo sapiens	Q15746 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9MXD_1 Calmodulin-1 (chains A)
MADQLTEEQIAEFKEAFSLFDKDGDGTITTKELGTVMRSLGQNPTEAELQDMINEVDADG
NGTIDFPEFLTMMARKMKDTDSEEEIREAFRVFDKDGNGYISAAALRHVMTNLGEKLTDE
EVDEMIREADIDGDGQVNYEEFVQMMTAK

Sequence of entity 2 (B), FASTA

>9MXD_2 Myosin light chain kinase, smooth muscle, deglutamylated form (chains B)
RRKWQKTGNAVRAIGRLSSM

Ligands and cofactors

ID	Name	Formula	Copies
CA	Calcium ion	Ca	4

Primary citation

Human E104A calmodulin:MLCK RM20 complex. Brunzelle, J.S., Shuvalova, L., Watterson, D.M. To be published.

Other PDB entries of the same protein (UniProt P0DP23 (AlphaFold model), which also has an AlphaFold model), best resolution first:

7BF1 1.24 Å, Ca2+-Calmodulin in complex with peptide from brain-type creatine kinase in extended 1:2…
6XXX 1.25 Å, 1.25 Angstrom crystal structure of Ca/CaM A102V:RyR2 peptide complex
4DJC 1.35 Å, 1.35 A crystal structure of the NaV1.5 DIII-IV-Ca/CaM complex
7BF2 1.43 Å, Ca2+-Calmodulin in complex with human muscle form creatine kinase peptide in extended…
2F3Y 1.45 Å, Calmodulin/IQ domain complex
2W73 1.45 Å, High-resolution structure of the complex between calmodulin and a peptide from…
4LZX 1.5 Å, Complex of IQCG and Ca2+-free CaM
5V03 1.58 Å, A positive allosteric modulator binding pocket in SK2 ion channels is shared by Riluzole…
9MVW 1.58 Å, Crystal structure of S101F calmodulin - CaM:RM20 analog complex
2F3Z 1.6 Å, Calmodulin/IQ-AA domain complex
6M7H 1.6 Å, Structure of calmodulin with KN93
6DAD 1.65 Å, 1.65 Angstrom crystal structure of the N97I Ca/CaM:CaV1.2 IQ domain complex

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