[BiO BB] Domain recognition

[nabula easter]

hi, 
 how easy is to find a domain in protein. 
is there any protocol in identifying protein. i have a
protein which is related to dolichyl -
transferase,which do not have any domain , now when i
do PSI-BLAST i find some other proteins which has some
identical and similar areas ? does this mean that
there is a domain in these proteins. 
 would you please help me pointing any protocol to
finalise any putative domain. IF i am looking at a
novel domain how to validate that domain ?
 please suggest any publications where the rules are
mentioned 
thank you 
Easter

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