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PDBsum entry 1tlk
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Calmodulin-binding
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PDB id
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1tlk
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References listed in PDB file
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Key reference
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Title
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X-Ray structure determination of telokin, The c-Terminal domain of myosin light chain kinase, At 2.8 a resolution.
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Authors
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H.M.Holden,
M.Ito,
D.J.Hartshorne,
I.Rayment.
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Ref.
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J Mol Biol, 1992,
227,
840-851.
[DOI no: ]
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PubMed id
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Abstract
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The three-dimensional structure of telokin, an acidic protein identical to the
C-terminal portion of smooth muscle myosin light chain kinase from turkey
gizzard, has been determined at 2.8 A resolution and refined to a
crystallographic R-factor of 19.5% for all measured X-ray data from 30 A to 2.8
A. Crystals used in the investigation belonged to the space group P3(2)21, with
one molecule per asymmetric unit and unit cell dimensions of a = b = 64.4 A and
c = 50.6 A. Telokin contains 154 amino acid residues, 103 of which were visible
in the electron density map. The overall molecular fold of telokin consists of
seven strands of antiparallel beta-pleated sheet that wrap around to form a
barrel. There is also an extended tail of eight amino acid residues at the N
terminus that does not participate in beta-sheet formation. The beta-barrel can
be simply envisioned as two layers of beta-sheet, nearly parallel to one
another, with one layer containing four and the other three beta-strands. This
type of beta-barrel, as seen in telokin, was first observed for the CH2 domain
of an immunoglobulin fragment Fc. Telokin is an intracellular protein and, as
such, does not contain the disulphide linkage between beta-strands B and F
normally observed in the immunoglobulin constant domains. It does, however,
contain two cysteine amino acid residues (Cys63 and Cys115) that are situated at
structurally identical positions to those forming the disulphide linkage in the
immunoglobulin constant domain.
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Figure 1.
Figure 1. Schematic representation of the rrangement of regulatory and functional domains in smooth muscle yosin
light chain kinase based on genetic and biochemical studies (Olsen et al., 1990) ad their relationship to telokin. The
Figure shows the positins of the immunoglobuin-like sequence motifs types I and II) that are omologous to those
observed in twitchin (Benian et al., 1989). t also ives the location in the sequnce of the catalytic and calmodulin
binding domains (CAM). The segmen responsible for auto-inhibition o MLCK is ocated between residues 786 and 805
and overaps the calmodulin binding region (Ito et al., 1991).
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Figure 10.
Figure 10. Superpsition of telokin and PapD. The superposition shown was generated as described for Fig. 7. X-ray
co-ordinates for the PapD molecule were graciousl supplied by Dr Carl Briinden. Telokin and PapD are shown in
continuous nd open bonds, respectivel.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(1992,
227,
840-851)
copyright 1992.
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