I was wondering how many of the files in the Protein Data Bank (PDB) have unknown function. The only paper I can find from an internet search is this one from 2012, which I assume might be outdated. I’d welcome suggestions of how to find this information for myself.
The article cited in the question indicates that the authors searched the PDB with the term “unknown function”. There is nothing special about this — you just type in the standard search field and hit ‘Go’. I conducted a search of this type myself:
Which returned 4384 structures out of approx. 149,600 in the data bank.
Of course, it is evident from the first page of the results that the number of unique proteins is smaller than this because a single study may examine different forms of the same protein.
I admit that I was surprised to find that people had spent time and money determining the structure of so many proteins of unknown function, but it appears that there is at least one blanket initiative to determine the structures of bacterial proteins of unknown functions because of their roles as potential pathogens. The idea would seem to be that they even if their mechanism of pathogenicity is unknown they could still be targeted on the basis of their structure.