Req: Definition of a promoter showing tissue specificity

[GWDGV1::KCHOWDH]

Martin Leach writes :
Doest the promoter have to show a decrease in relative reporter activity...and a lack of orientation 
specificity in addition to this?

Hi Martin,
If the promoter is tissue specific, in vivo (animals),it should certainly show decreased or complete 
lack of activity in other tissues.  However , in in vitro (cell culture) the situation could be more
complex, because of the possible lack (or presence) of some proteins factors which interact with the 
transcription machinery and are different in the animal tissue. In other words, cell culture may not 
reflect the true in vivo situation.

I dont know what you mean by "lack of orientation specificity".  Most promoters are unidirectional,
however, there are also known cases of bidirectional promoters.

Cheers,

Kamal Chowdhury