A fundamental limitation of structural genomics is
that it typically only provides clues about molecular
function6, such as what a protein binds to or reacts with.
Understanding this molecular function gives only limited
insight into the cellular role. This limitation is endemic
to homology-based methods and is therefore shared
with sequence comparison. Fortunately, many other
functional genomics approaches, especially expression
profiling, yield precisely complementary data: although
they cannot indicate the molecular action of a protein,
they provide clues about its role in a wider context, such
as in a signalling pathway or a cellular state.