Dakota Johnson will play Anastasia Steele in the big-screen adaptation of E L James' "Fifty Shades of Grey."

Focus Features and Universal Pictures announced the casting Monday. The 23-year-old Johnson is a relatively unknown actress who has had small roles in "The Social Network" and "21 Jump Street." She's the daughter of actors Don Johnson and Melanie Griffith.

In the erotic romance, Steele is a college student who undergoes a sexual awakening. Yet to be announced is the actor who will play the male lead of 27-year-old billionaire Christian Grey.

Directed by Sam Taylor-Johnson, the film is to be released next August.