Now we will start to look at information about specific protein structures. Each entry in the Protein Data Bank is given a code which consists of 4 characters (letters or numbers) e.g. 2brd, 4fxn etc. If we happen to know the code, then we can search based on this. Even if we don't, once we have found a particular structure of interest by other means (see later), we can use the 4-character code as a reference to come back to the same structure at a later date.
As an example we are going to search using one particular code and find information about the structure it corresponds to. In the search box at the top of the PDB home page, type the following PDB code: 2dn2 and click 'Site search'. A new window will appear showing the entry for this code. Navigate around this entry and answer the questions.