<s>
Modeller	B-Application
,	O
often	O
stylized	O
as	O
MODELLER	B-Application
,	O
is	O
a	O
computer	B-Application
program	I-Application
used	O
for	O
homology	O
modeling	O
to	O
produce	O
models	O
of	O
protein	O
tertiary	O
structures	O
and	O
quaternary	O
structures	O
(	O
rarer	O
)	O
.	O
</s>
<s>
It	O
implements	O
a	O
method	O
inspired	O
by	O
nuclear	O
magnetic	O
resonance	O
spectroscopy	O
of	O
proteins	O
(	O
protein	O
NMR	O
)	O
,	O
termed	O
satisfaction	O
of	O
spatial	O
restraints	O
,	O
by	O
which	O
a	O
set	O
of	O
geometrical	O
criteria	O
are	O
used	O
to	O
create	O
a	O
probability	O
density	O
function	O
for	O
the	O
location	O
of	O
each	O
atom	B-Language
in	O
the	O
protein	O
.	O
</s>
<s>
The	O
method	O
relies	O
on	O
an	O
input	O
sequence	B-Algorithm
alignment	I-Algorithm
between	O
the	O
target	O
amino	O
acid	O
sequence	O
to	O
be	O
modeled	O
and	O
a	O
template	O
protein	O
which	O
structure	O
has	O
been	O
solved	O
.	O
</s>
<s>
Modeller	B-Application
was	O
originally	O
written	O
and	O
is	O
currently	O
maintained	O
by	O
Andrej	O
Sali	O
at	O
the	O
University	O
of	O
California	O
,	O
San	O
Francisco	O
.	O
</s>
<s>
It	O
runs	O
on	O
the	O
operating	O
systems	O
Unix	B-Application
,	O
Linux	B-Application
,	O
macOS	B-Application
,	O
and	O
Windows	B-Application
.	O
</s>
<s>
It	O
is	O
freeware	B-License
for	O
academic	O
use	O
.	O
</s>
<s>
Graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUIs	B-Application
)	O
and	O
commercial	B-Application
versions	O
are	O
distributed	O
by	O
Accelrys	O
.	O
</s>
<s>
The	O
ModWeb	O
comparative	O
protein	O
structure	O
modeling	O
webserver	O
is	O
based	O
on	O
Modeller	B-Application
and	O
other	O
tools	O
for	O
automatic	O
protein	O
structure	O
modeling	O
,	O
with	O
an	O
option	O
to	O
deposit	O
the	O
resulting	O
models	O
into	O
ModBase	O
.	O
</s>
<s>
Due	O
to	O
Modeller	B-Application
's	O
popularity	O
,	O
several	O
third	O
party	O
GUIs	B-Application
for	O
MODELLER	B-Application
are	O
available	O
:	O
</s>
<s>
EasyModeller	O
is	O
freeware	B-License
and	O
is	O
one	O
of	O
the	O
earliest	O
third	O
party	O
GUIs	B-Application
for	O
Modeller	B-Application
.	O
</s>
<s>
Recent	O
version	O
(	O
EasyModeller	O
4.0	O
)	O
supports	O
Linux	B-Application
and	O
Windows	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
UCSF	B-Application
Chimera	I-Application
has	O
a	O
simple	O
interface	O
to	O
Modeller	B-Application
.	O
</s>
<s>
PyMod	O
is	O
a	O
free	B-Application
and	I-Application
open-source	I-Application
plugin	O
for	O
PyMOL	B-Application
and	O
has	O
a	O
comprehensive	O
interface	O
for	O
Modeller	B-Application
.	O
</s>
<s>
It	O
supports	O
Linux	B-Application
,	O
Windows	B-Application
and	O
macOS	B-Application
.	O
</s>
<s>
MaxMod	O
is	O
a	O
standalone	O
GUI	B-Application
for	O
MODELLER	B-Application
on	O
Windows	B-Application
.	O
</s>
