Google Subscribed Links provide a mechanism for adding information at the top of a Google search results page. I set up an example that can be used to see information from the Enzyme Nomenclature Database when searching for something like EC 18.104.22.168.
If you subscribe to this additional information, this is what should appear at the top of the results for the query mentioned above:
Google requires that you provide them with a static document that describes what to show for which queries – I assume forwarding queries to a server would be a performance and privacy problem. To produce this document (large!) I used:
enzymes.rdf.gz document from the latest UniProt RDF distribution
– The expasy4j Java library for parsing this document
Once the location of this document was submitted to Google, the document was crawled and (later) updated automatically.