There are two key food allergens found in macadamia nuts, Mac i 1 and Mac i 2.
Mac i 1 is a vicilin like protein used in storage in the plant. This is also sometimes described as a 7S seed storage protein.
Mac i 2 is a legumin like protein, this is similar to the protein casein in milk. This is also often described as an 11S seed storage protein.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Macadamia.php
The allergy resources page for macadamia nut covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with macadamia nut.
There is also regularly updated links to useful websites specifically for macadamia nut 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.