Proteins are the central machines of cells, and they perform
their actions by interacting with each other as well as with
other molecules.  Large complexes involving tens or even
hundreds of proteins make up the central hubs in biological
interaction networks.  In human cells repeated domains are
frequent among these hubs. Today, large-scale efforts in
genomics, proteomics, lipidomics and metabolomics are
producing complete lists of the molecules in entire cell as
well as in different sub-cellular compartments. Further,
interactions between molecules can be studied at different
levels of detail.  In small-scale studies it is possible to
obtain detailed information about the interaction of a few
molecules, while in large-scale studies less detailed
information for a larger set of molecules can be obtained.
Only for a small number of the large complexes atomistic
details have been possible to obtain and in particular
molecular complexes embedded in the membrane have been
difficult to study experimentally.

A major aim within the field is to reveal detailed
structural information about large biological complexes. To
obtain this goal a mix of experimental and computational
methods needs to be applied.  A major source of information
is coming from the rapid increase in genomic sequence data.
 Here, I will discuss how to combine computational and
experimental studies  to obtain increased understanding of
the formation of large molecular complexes particularly in
the membrane.