Black walnuts have 3 key allergens, Jug n 1 (2S albumin protein), Jug n 2 (vicilin like protein) and Jug n 4 (legumin protein).
English walnuts have 8 identified allergens, which in addition to the proteins above also has PR-10 (proteins involved in oral allergy syndrome), 11S storage proteins, profilin proteins and 2 lipid transfer proteins (LTP).
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Walnut.php
The allergy resources page for walnut covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with walnut.
There is also regularly updated links to useful websites specifically for walnut allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.