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IMP Reference Guide  2.20.2
The Integrative Modeling Platform
membrane.py
1 ## \example pmi/membrane.py
2 """
3 This script shows how to simulate an a protein using a
4 Membrane restraint. This example show 3 ideal helices
5 that have different segments inside the membrane
6 """
7 
8 import IMP
9 import IMP.atom
10 import IMP.rmf
11 import IMP.pmi
12 import IMP.pmi.topology
13 import IMP.pmi.dof
14 import IMP.pmi.macros
15 import IMP.pmi.restraints
19 import sys
20 
21 IMP.setup_from_argv(sys.argv,
22  "Simulation of a protein using a membrane restraint")
23 
24 model = IMP.Model()
25 s = IMP.pmi.topology.System(model)
26 st = s.create_state()
27 
28 # Create molecules and add helix representation
29 # this makes a c-alpha chain in approximately the shape of a helix
30 mols = []
31 
32 for i, len_helix in enumerate([20, 40, 80]):
33  mol = st.create_molecule(
34  "helix_%s" % (str(i)), sequence="A" * len_helix, chain_id="A"
35  )
36  mol.add_representation(mol, resolutions=[1], ideal_helix=True)
37  mols.append(mol)
38 hier = s.build()
39 
41 for mol in mols:
42  dof.create_rigid_body(mol,
43  max_trans=3.0,
44  max_rot=0.5)
45 ##############################
46 # Connectivity
47 ##############################
48 output_objects = []
49 sample_objects = []
50 rmf_restraints = []
51 
52 crs = []
53 for mol in mols:
55  cr.set_label(mol.get_name())
56  cr.add_to_model()
57  output_objects.append(cr)
58  crs.append(cr)
59 
60 ##############################
61 # Excluded Volume
62 ##############################
64  included_objects=mols, resolution=1
65 )
66 evr1.add_to_model()
67 evr1.set_weight(1.0)
68 output_objects.append(evr1)
69 
70 ##############################
71 # Membrane restraint
72 ##############################
73 
75  hier,
76  objects_inside=["helix_0", (1, 20, "helix_1"), (20, 40, "helix_2")],
77  objects_above=[(21, 40, "helix_1"), (1, 19, "helix_2")],
78  objects_below=[(41, 80, "helix_2")],
79  weight=10,
80 )
81 
82 mr.add_to_model()
83 output_objects.append(mr)
84 
85 # For visualization purposes
86 mr.create_membrane_density()
87 
88 ###########################
89 # External barrier
90 ###########################
91 eb = IMP.pmi.restraints.basic.ExternalBarrier(hierarchies=hier, radius=50)
92 eb.add_to_model()
93 
94 ##############################
95 # Shuffle
96 ##############################
97 IMP.pmi.tools.shuffle_configuration(hier, max_translation=300)
98 print(dof.get_movers())
99 
100 ##############################
101 # Sampling
102 ##############################
103 
104 frames = 10 if IMP.get_is_quick_test() else 2000
106  model, root_hier=hier, monte_carlo_sample_objects=dof.get_movers(),
107  replica_exchange_maximum_temperature=3.0,
108  global_output_directory="output/", output_objects=output_objects,
109  monte_carlo_steps=10, number_of_frames=frames,
110  number_of_best_scoring_models=0)
111 
112 rex.execute_macro()
113 exit()
Simplify creation of constraints and movers for an IMP Hierarchy.
Restraints for keeping correct stereochemistry.
bool get_is_quick_test()
Definition: flags.h:183
def shuffle_configuration
Shuffle particles.
Definition: tools.py:1258
A macro to help setup and run replica exchange.
Definition: macros.py:68
Set of Python classes to create a multi-state, multi-resolution IMP hierarchy.
Strings setup_from_argv(const Strings &argv, std::string description, std::string positional_description, int num_positional)
Some miscellaneous simple restraints.
Protocols for sampling structures and analyzing them.
Definition: macros.py:1
Represent the root node of the global IMP.atom.Hierarchy.
Class for storing model, its restraints, constraints, and particles.
Definition: Model.h:86
Classes to handle different kinds of restraints.
Restrain particles to be above, below, or inside a planar membrane.
Keeps all structures inside a sphere.
Create a restraint between consecutive TempResidue objects or an entire PMI Molecule object...
Create movers and set up constraints for PMI objects.
A class to create an excluded volume restraint for a set of particles at a given resolution.
Python classes to represent, score, sample and analyze models.
Functionality for loading, creating, manipulating and scoring atomic structures.
Support for the RMF file format for storing hierarchical molecular data and markup.