It depends on the bean. Some beans are not really beans but more like peas. Google tells me this about read beans, https://www.google.com/search?q=pro...&oe=&gws_rd=ssl , 43g per cup.

I'm on travel right now but something did occur to me that I wanted to ask, is an Atkins discussion board the best place to ask about low protein requirements? I would imagine that most of us go over our protein requirements and have little experience with insufficient protein.