I have the human protein .I need to find its interacting partners that is I need to find that which proteins it is interacting with for regulation and what are the sites within this protein where it interacts with these proteins .If there is any database for such type of information kindly suggest.
What you want to do can be be done only on a case-by-case basis, as there is no database that contains information about interacting residues for ALL protein complexes. This is because most protein complexes have not be characterized at that level of detail.
You already have a STRING suggestion, which will tell you the likely interacting partners. From that point on you may have to be content with predicting interacting residues. To do that, there is a website that measures evolutionary couplings:
It only provides the network of proteins interacting with the given protein but what I need is also the residue information that are interacting between the two proteins .