When I'm using auctex with emacs to write LaTeX documents, I would like to be able to add a couple more options to the list of environment types that auctex "recognises" and can autocomplete, namely Theorem, Lemma, Proof, itemize* and a couple of others. Which variable to I need to edit? I have played around in customize-apropos LaTeX and auctex, but I haven't found it.

(lisp code snippet to add to my .emacs would be preferred, I don't quite understand the syntax yete)