Gwyneth Paltrow has signed on to The Danish Girl, a film chronicling the real-life story of the world's first post-operative transsexual, Einar Wegener.

Actress Gwyneth Paltrow, pictured here in February in New York City, will portray a painter who asks her husband to pose as a woman, starting his journey to becoming one. (Evan Agostini/Associated Press)

Wegener will be portrayed by Nicole Kidman, and Paltrow will play Wegener's wife, Greta, a portrait painter who one day asked her husband to stand in for a female model.

Charlize Theron was originally tied to the role but dropped out for unspecified reasons. Kidman is also one of the film's producers.

Greta Wegener's illustrations of her husband dressed as a woman soon became popular, so the artist began asking him to fill in more and more.

Around 1913, the world discovered that Wegener's works of women were based on her husband.

Einar Wegener, an artist himself, eventually took on the name of Lili Elbe and appeared in public regularly as a woman. The pair, who had married in 1904, initially remained together.

But their marriage was dissolved in 1930, and soon after, Einar Wegener went through a series of five sex reassignment operations in Germany. Months after her final operation, in 1931, she died.

Swedish director Thomas Alfredson — whose 2008 child vampire movie Let the Right One In was highly acclaimed — is directing a script based on an adaptation of a bestselling 2001 novel by David Ebershoff.

Alfredson's vampire film, also based on a novel, featured a child vampire whose gender is deliberately portrayed as ambiguous.

The Danish Girl is due for release in 2011.