  Gene expression and regulation rely on an apparently finely tuned set of
reactions between some proteins and DNA. Such DNA-binding proteins have to find
specific sequences on very long DNA molecules and they mostly do so in absence
of any active process. It has been rapidly recognized that to achieve this task
these proteins should be efficient at both searching (i.e. sampling fast
relevant parts of DNA) and finding (i.e. recognizing the specific site). A
two-mode search and variants of it have been suggested since the 70s to explain
either a fast search or an efficient recognition. Combining these two
properties at a phenomenological level is however more difficult as they appear
to have antagonist roles. To overcome this difficulty, one may simply need to
drop the dihcotomic view inherent to the two-mode search and look more
thoroughly at the set of interactions between DNA-binding proteins and a given
DNA segment either specific or non-specific. This chapter demonstrates that, in
doing so in a very generic way, one may indeed find a potential reconciliation
between a fast search and an efficient recognition. Although a lot remains to
be done, this could be the time for a change of paradigm
