PDBsum entry 3cln

Calcium binding protein

PDB id: 3cln

Contents

Protein chain

143 a.a.

Metals

_CA ×4

Waters ×69

References listed in PDB file

Key reference

• Title: Structure of calmodulin refined at 2.2 a resolution.
• Authors: Y.S.Babu, C.E.Bugg, W.J.Cook.
• Ref.: J Mol Biol, 1988, 204, 191-204.
• PubMed id: 3145979

Abstract

The crystal structure of mammalian calmodulin has been refined at 2.2 A (1 A = 0.1 nm) resolution using a restrained least-squares method. The final crystallographic R-factor, based on 6685 reflections in the range 2.2 A less than or equal to d less than or equal to 5.0 A with intensities exceeding 2.5 sigma, is 0.175. Bond lengths and bond angles in the molecule have root-mean-square deviations from ideal values of 0.016 A and 1.7 degrees, respectively. The refined model includes residues 5 to 147, four Ca2+ and 69 water molecules per molecule of calmodulin. The electron density for residues 1 to 4 and 148 is poorly defined, and they are not included in the model. The molecule is shaped somewhat like a dumbbell, with an overall length of 65 A; the two lobes are connected by a seven-turn alpha-helix. Prominent secondary structural features include seven alpha-helices, four Ca2+-binding loops, and two short, double-stranded antiparallel beta-sheets between pairs of adjacent Ca2+-binding loops. The four Ca2+-binding domains in calmodulin have a typical EF hand conformation (helix-loop-helix) and are similar to those described in other Ca2+-binding proteins. The X-ray structure determination of calmodulin shows a large hydrophobic cleft in each half of the molecule. These hydrophobic regions probably represent the sites of interaction with many of the pharmacological agents known to bind to calmodulin.

Secondary reference #1

• Title: Three-Dimensional structure of calmodulin.
• Authors: Y.S.Babu, J.S.Sack, T.J.Greenhough, C.E.Bugg, A.R.Means, W.J.Cook.
• Ref.: Nature, 1985, 315, 37-40.
• PubMed id: 3990807

Secondary reference #2

• Title: Preparation of calmodulin crystals.
• Authors: W.J.Cook, J.S.Sack.
• Ref.: Methods Enzymol, 1983, 102, 143-147. [DOI no: 10.1016/S0076-6879(83)02015-7]
• PubMed id: 6645968

Secondary reference #3

• Title: Chicken calmodulin genes. A species comparison of cdna sequences and isolation of a genomic clone.
• Authors: J.A.Putkey, K.F.Ts'Ui, T.Tanaka, L.Lagacé, J.P.Stein, E.C.Lai, A.R.Means.
• Ref.: J Biol Chem, 1983, 258, 11864-11870.
• PubMed id: 6137485

Secondary reference #4

• Title: Crystallization and preliminary X-Ray investigation of calmodulin.
• Authors: W.J.Cook, J.R.Dedman, A.R.Means, C.E.Bugg.
• Ref.: J Biol Chem, 1980, 255, 8152-8153.
• PubMed id: 7410353