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From left, Gaby Hoffmann, Jeffrey Tambor, and Jill Soloway speak onstage during the "Transparent" panel at the Amazon 2014 Summer TCA on Saturday, July 12, 2014, in Beverly Hills, Calif. Image Credit: Richard Shotwell/Invision/AP

Having marked his 70th birthday earlier this week, Jeffrey Tambor is celebrating what he calls his most “transformative” role. The veteran actor plays a man who, late in life, acts on his long-suppressed need to be a woman.

The new transgender drama-comedy, Transparent, premieres in late September with all 10 episodes of its first season on Amazon Prime Instant Video.

Tambor, well-known from comedies Arrested Development and The Larry Sanders Show, here has the dramatic challenge of portraying a man at a life-changing moment as he breaks the news to his adult children.

It’s the story “of one parent who dies as a new parent is born,” said series creator Jill Soloway, whose credits include Six Feet Under and the film Afternoon Delight.

The series also stars Jay Duplass, Gaby Hoffmann, Amy Landecker and Andrea Sperling.

“This is all I ever wanted to do,” said Tambor, summing up his role for reporters at a Saturday session of the summer TV critics’ tour. “I’m overwhelmed and having the time of my life.”

Amazon’s slate of new original online fare also includes Mozart in the Jungle, a comedy about a symphony orchestra, the thriller The After, from The X-Files creator Chris Carter, and Bosch, a detective drama starring Titus Welliver.